We shop throughout. If it's something I know I can get at the Emporium/Mouse Gears/Outfitters, and I see it somewhere else early in the day, I'll wait to buy it until the end of the day, but I never put it off til another day because you never know when your plans will change and you might not be back to that park. If we are on a longer trip, we'll buy whenever and have it sent to our resort, which is nice. If it's something we might not find anywhere else (a ride-themed gift shop, for example) we buy it then and there and store it in a locker or in the stroller. I've found in-park pick-up to be too much of a hassle (for us), so we don't utilize that anymore.