Work from the issuer’s rule
Suppose a club needs a headcount “two days before the picnic.” Write down both the picnic date and the requested headcount deadline. If the picnic moves, confirm whether the deadline moves with it before changing the task. Imagine a picnic on June 12 and a headcount due two calendar days before. June 10 follows from that wording. If the notice instead says “by noon on June 9,” use its stated deadline.
Keep calculation and action separate
Write “Reply with headcount” as a task for the adult who will send it. Put the exact source rule beside it and record any stated time or time zone. If the rule uses business days, ask how the issuer treats weekends, holidays and the event day rather than importing your household’s work calendar.
When the event moves
Check for an explicit replacement deadline. Some organizers move the event but keep the old headcount date because catering is already booked. Update the task after confirmation and notify whoever owns it. If you create an earlier personal reminder, mark it as your reminder, not the issuer’s rule.