We just did this last week. Our PS was for 7:30. Epcot was very crowded with Food & Wine Festival, and there were lines for checking in....so we showed up at 7:00 just to make sure. I said something like: we were early but when we had walked by earlier it was packed, so better safe then sorry. I politely asked for an outdoor table, but I also said I know it may not be possible but it's worth asking.
They gave us a beeper/pager thing and said stay in the UK, it would be a wait because we were early. It wasn't even 10 or 15 minutes and we got paged...we got a great lakeside seat outside. I was concerned because it was early, but the kitchen was backed up because of the crowds. We ordered appetizers, salad and entree and were having desert and coffee during Illuminations. I didn't mind the long 2 hour dinner because it was just me and my mom, no kids, so we had some wine and just relaxed. It was magical!