I made Panna Cotta for a party. I don't have a fridge where I'll keep them, so most likely they'll be on a buffet table. I'm afraid of them going bad or becoming liquid (Or something like that) after sitting out of the fridge more than 4 hours I guess? I also know you shouldn't keep cooked food more than 4 hours out of the fridge but yes. Does anyone know?
Pack them in a cooler with ice (or freezer packs) and keep them in there as long as you can. Let them be the last thing you put on the buffet... just before the guests arrive.
You could also nestle them in a buffet pan full of ice, so they are displayed in a way that makes them accessable for guests, but also keeps them from spoiling.