I think for me, I get the feeling of vacation starting when the car is backing out of the driveway. All the planning and packing ahead of time doesn't trigger it since it's still all mixed in with work and other usual daily tasks. This could also be because our trips aren't very structured, there is no specific itinerary, we roll with the flow.
Curiously, I don't find the reverse to be true: vacation is over NOT when we're back home, but when we start the drive back home. I'm going to chalk that up to the fun stuff being over, and our return trip is usually all business. Put in the miles, pit stops only, no other destination stops, just getting home as the singular goal.
one or more gifts or other benefits from the co-op.