A headcount message fails when it invites a soft 'maybe' and you book on it. Include a firm response deadline, state the cost, and give people an easy way to mention accessibility needs.
By pingpong ·
A text to start with
Draft a headcount message for a group day trip to [destination] on [date]. Transport is a chartered van for 15 people, and the cost is [amount] per person, paid in advance. I need a confirmed yes or no by [deadline]. Include a line where people can note accessibility needs privately. Say that we can't hold spots without payment. Do not imply anything is booked; we're still confirming numbers.
Example request. Change the details to fit your situation.
What to check before sending
Make sure the draft does not say or suggest that the van is booked, the trip is confirmed, or spots are guaranteed. The cost and deadline should appear exactly as you gave them. Word the accessibility line so people can reply to you privately, not in a group thread. If capacity is limited, the message can say so plainly without adding pressure.
Moving to confirmed booking
Once responses reach your minimum, compile the confirmed list and ask the assistant for a follow-up with payment instructions and trip details. Keep a separate note of anyone who said yes but has not paid, and settle your waitlist policy before the deadline passes.