I'm taking my dd, 31, to WDW for her very first time in Jan...think I'll put your statements to the test. I'll ask at checkin and see what happens, although I think it's kinda rude to do then, at the last minute. I would think it would be better to request it when you make the reservation, with a note on the reservation so the room assigners would see it and make a note of it. But, I could be way off base.
So...what happens if you get to POP checkin at noon, ask for balloons for your room due to whatever special thing, and your room is ready right then? Does a CM go running off to beat you to the room? Or do they tell you the room will be ready in about 30 mins? I'm not trying to be argumentative, just really curious.