Plan backwards from the date and see what this week needs

Some work comes with a date nobody will move: a training day, a product launch, the end of term, an annual report, an office move, an audit, a fundraising dinner. The big tasks get planned. The trouble comes from the small ones that surface late, like the printer who needs eight business days in December or the budget that only gets approved at Tuesday’s meeting. You find out with six days left, and the last week turns into a scramble.

A backward plan finds those tasks while there’s still time to deal with them. You give an AI assistant the date, what must be true on that day and the constraints you know about, and it works back to today in a dated table. Then you check its guesses with the people who will do the work. By the end of today you’ll have this week’s tasks in your calendar, and the questions that could still move the plan will already be on their way.

Why start from the date

With a fixed date, what you’re really choosing is when each task has to start. Working back gives every task a latest start, so the ones due this week show up today instead of in week six, and a start date that has already passed shows up while you can still cut something or find help.

If you run the same event every year, last year’s plan with new dates beats any first draft from an assistant. Use that, and ask the assistant only for the “usually forgotten” list below.

What to give the assistant

An assistant knows roughly how an event or a launch goes. It doesn’t know your printer or who’s on leave in November, and unless you tell it, it fills those gaps with numbers that sound reasonable. Write down:

• The date, with its weekday and time. “Thursday, December 10, 9:00” catches mistakes that “mid-December” hides.
• What must be true on that day, in four to eight lines written as finished states: “venue set up for 80”, “workbooks printed and in the room”. The plan is built from this list, so anything missing here is missing there.
• The constraints you know about: approvals, supplier lead times, leave, budget and the public holidays before the date. Take the holidays from your country’s official calendar rather than from the assistant.

The prompt

It works in Claude, ChatGPT, Gemini or Copilot. Fill in the brackets and delete what doesn’t apply.

Today is [weekday, date]. I'm planning backwards from a fixed date.

The date: [weekday, date, time]
What it is: [one line]
What must be true on that day:
- [finished state]
- [finished state]
Constraints I know about:
- Approvals: [who signs off, and how long it takes]
- Suppliers and lead times: [what you've been told, or "unknown"]
- Public holidays before the date: [from the official calendar]
- Leave: [who, which dates]
- Other: [budget, busy periods, anything fixed]
People involved: [names and roles]

Work backwards from the date and make a table with these columns:
# | Task | Owner | Business days | Start | Finish | Depends on | Assumption

Rules:
- Count business days only, Monday to Friday, and skip the holidays and leave above.
- Write every date with its weekday, like "Thu Oct 22".
- Every duration is an assumption. In the Assumption column, say what it depends on and who could confirm it.
- Use only the owners I named. If no one fits, write UNASSIGNED.
- Sort the table by start date.
- If any start date has already passed, list those tasks first under "Already late" and suggest what could be cut, shortened or run in parallel.

After the table, add three short lists:
1. Starts this week: tasks that must start in the next five business days.
2. Usually forgotten: ten things people often forget when planning this kind of work that are not in my list, each with the date it would need to start.
3. Questions to ask: one question for each person or supplier, to confirm the durations that matter most.

If your weekend isn’t Saturday and Sunday, change “Monday to Friday”. Today’s date is in the prompt because not every assistant knows it. The weekday rule is there because assistants can slip on calendar arithmetic, putting a task on a Sunday or counting straight through a holiday, and a weekday next to each date makes those slips easy to spot.

Read the “usually forgotten” list before the table. That’s where things like name badges and the venue’s final invoice turn up, too small to plan until the day they’re missing.

If the plan involves something not yet public, such as a reorganization, use a code name or first check what your assistant’s plan allows (Before you upload a client document lists the questions).

Turn every duration into a question

The draft looks finished, with dates down to the day, and that’s the risk: every number in the Business days column is a guess about someone else’s work. Ask suppliers about the month you actually need (“How many business days from final files to delivery, in December?”), since lead times can stretch in a busy season. Ask approvers when an answer would come if the request reached them on Monday, and ask colleagues whether the time fits around everything else they have that week.

Send the “Questions to ask” list today, one short message per person. As answers arrive, update the durations, then check two things: no task starts before the one it depends on has finished, and nothing lands on a weekend, a holiday or someone’s leave.

A worked example

Everything here is made up. On Thursday, October 15, Elena, who coordinates training at a company of 200 people, learns there will be a training day for 80 staff on Thursday, December 10, at a venue that isn’t booked yet. Her “must be true” list includes two trainers confirmed, everyone registered with dietary needs known, and a printed workbook for each person. Her constraints: Marta in finance approves the budget, Sam from her team is on leave November 23 to 27, and her office has a public holiday on Monday, November 16.

The assistant’s table, trimmed to fit this page:

#   Task                          Owner     Days  Start       Finish
1   Budget approval               Marta     5     Thu Oct 15  Wed Oct 21
2   Confirm both trainers         Elena     3     Thu Oct 15  Mon Oct 19
3   Book venue, pay deposit       Elena     3     Thu Oct 22  Mon Oct 26
4   Invitations and sign-up form  Sam       2     Tue Oct 27  Wed Oct 28
5   Workbook content              Trainers  15    Tue Nov 3   Tue Nov 24
6   Layout and proofreading       Elena     5     Wed Nov 25  Tue Dec 1
7   Final numbers to caterer      Elena     1     Mon Nov 30  Mon Nov 30
8   Printing and delivery         Printer   3     Wed Dec 2   Fri Dec 4
9   Reminder with agenda and map  Sam       1     Thu Dec 3   Thu Dec 3
10  Set-up check at the venue     Elena     1     Wed Dec 9   Wed Dec 9

Its “usually forgotten” list included asking about dietary and accessibility needs on the sign-up form, who opens the venue and how early, name badges for the door, and approval to pay the venue’s final invoice.

Elena sent her questions before lunch, and two answers came back the same afternoon. The printer needs eight business days in December, not three. Counted back from Friday, December 4, printing now starts November 25 and layout November 18, so the trainers’ content is due Tuesday, November 17 instead of the 24th. Marta signs approvals only at her Tuesday meeting: if the request doesn’t reach her by Monday, October 19, the venue booking slips a week. No assistant could have known either answer, and both changed what Elena does this week. Her calendar for the next few days:

Thu Oct 15  Budget request to Marta
Thu Oct 15  Email both trainers: date, content due Tue Nov 17
Fri Oct 16  Call two venues: provisional hold for Thu Dec 10
Mon Oct 19  Check: trainers confirmed? Request with Marta?

Choosing between the two venues is a small decision of its own, and a comparison table with a link behind every cell is a good way to make it.

Keep the plan current

Copy the table into a spreadsheet (if the columns land squeezed into one, ask for it as CSV and use your spreadsheet’s option to split text into columns). Book your calendar one week at a time, since the dates will move after the first round of answers.

To make the dates move by themselves, put each task’s business days in column C, its start in D and its finish in E, and list your holidays in H2:H10. For the task in row 2, these work in Excel and Google Sheets:

Start (D2):   =WORKDAY(E2, -(C2-1), $H$2:$H$10)
Finish (E2):  =WORKDAY(D3, -1, $H$2:$H$10)

The start formula counts back from the finish by the task’s length (the finish day itself counts, hence the minus one). The finish formula ends the task one business day before the task in row 3 starts; if the task that depends on it sits in another row, point it at that row’s start. Where a finish is fixed, such as “delivered by Friday, December 4”, type the date. Then change the printer’s 3 to an 8 and watch every date before it move. WORKDAY skips Saturdays, Sundays and the holidays you list; WORKDAY.INTL lets you choose a different weekend. To get formulas like these without writing them yourself, see Describe the formula you need in plain words.

Give the plan 15 minutes a week, at a fixed time. Mark what finished, update the durations you’ve learned more about, and look for start dates that have passed, because each one needs a decision now. Then book next week’s tasks. If you keep a running log for your weekly report, the review’s notes go straight into it.

Try it today

Pick one real deadline in the next three months with more than a handful of tasks behind it, and set aside an hour for it today.

1. Write the date with its weekday, your “must be true” lines and the constraints you know.
2. Run the prompt. Read “starts this week” and “usually forgotten” before the table.
3. Send the questions to the people who do the work.
4. Book this week’s tasks in your calendar, each with its finish date in the title, plus a recurring 15-minute review.

You’re done when this week’s tasks are in your calendar and the questions have gone out. If the answers show the date won’t hold, you’ve found out with weeks to spare instead of days.

Where this leads

A backward plan tells you what’s due this week, but not whether your week has room for it. Make next week fit in your calendar sets your “starts this week” list against the hours you actually have and ends with a list of what can wait. Once the plan is running, meetings are where it changes, and Take meeting notes in three letters turns each one into actions with owners and dates you can paste straight into the sheet.