The show starts at exactly 09:50. It doesn't really matter when you show up. 09:30 would be fine so you can get a drink, and go to the bathroom. Most food stands close at 09:30, so if you want something, get it before this time. Laurie wanted ice cream, and the window closed at 09:40 just as she walked up, whaaa. They could make more money if they stayed open until the end, but oh well. They play some really cool fusion jazz music before the show, so you'll be entertained while waiting.
There are only a couple fireworks that happen in the lagoon itself, where the pods shoot up white sparkle things. Everything else goes high up into the air, so you'll see it no matter where you are standing.
And there's no rush to leave afterwards. We took our time walking out, made it thru the gate with no problem, then walked on the path back to the RPR.