You can just show up. We only went once, but it seems like they just keep going from one thing to the next. There were characters, non-character dancers, and also DreamWorks trivia when we went. The characters will do their thing, and then pose with you (from a small distance) for photos. The stage is in the middle of the room, so you just go stand on the photo dot on the floor nearest the character you're interested in.
It's a little awkward because there is no seating, so you just go in and stand around (or dance if you're a kid... or kid at heart). There's no clear start or stop to the performance, so we felt a little strange walking in, and then leaving when they were still doing stuff (I felt rude, but had to rejoin the rest of my group). I don't think many people realize the show is back there, so there were more TMs than guests when we went. I kind of wanted to bring a whole bunch of people back because the performers were giving it their all, and I wish they had a good audience to feed off of.
