Newsletter
The first mention opens the trunk sign-up with the date, the hours and the three asks. The second mention is the trunk count against the target and the candy drop-off dates. The last call is the final count, the arrival time for hosts and the parking plan for guests.
Social
Save the date is the date, the hours and that it is free, on an image a neighbor can share. The reminder post the Friday before is the public one: hours, address, parking, rain plan. The day-of post goes out mid-afternoon with the hours and a photograph of the first trunks.
Sunday Announcements
Announce it two Sundays before with the trunk count and the candy ask. The final announcement is the Sunday before the Saturday: the host arrival time, the candy total, and the request that members park off site to leave the lot for guests.
Website
The public page: date, hours, address, parking, that it is free, the rain plan, and what a child needs (a bag, a costume). The trunk sign-up and the candy drop-off dates are on the same page under a heading for members. Published four weeks out.
Print
A yard sign at the road three weeks out, flyers for the neighborhood and the nearby schools, and a poster at the entrances. Due a week before they go up because the printer needs a week.