What day do you find folks more likely to buy guns you bring to a show to sell (carrying them around, not at a table) - the first day or the last, assumming a typical 2 day weekend show?      

My own limited experience is that ASAP works best. In the past year both I and a buddy I went to a show and sold our guns in the waiting line, before we even got into the show. Both times it was right at the beginning of the show on Saturday AM.  Also sold an AR upper in the parking lot as I was unloading my car on a Saturday morning.

Now I wouldn't call these experiences definitive. I very rarely try to sell anything at a show, but at least here in Atlanta Saturday morning seems to work [:D]

My observations at gun shows while working them selling my reactive targets suggests early on the first day is the best time to deal, especially to dealers.  That gives them plenty of time to sell the gun during the weekend, before they have to cart it home.