I do know from experience...keep the 7:30...and if you're lucky enough to get a table in the room with the windows, just plan on stretching your meal out (order drinks...don't order entree until after drinks come...don't order dessert until finished with entrees, etc.) The servers expect people to linger.
If you have the bad luck to get seated in the non-view room (about 1/3 of the tables) you can order & eat at the regular speed, you'll be out of there before 8:30 and have time to walk out & find a good viewing spot around the lagoon somewhere (walk towards the top of the World Showcase...closer to America--to find a spot to view...the area around Mexico will probably be packed because people like to be at that end of the World Showcase to make a quicker get-away after Illuminations.)
If you are seated in the non-view room, and for some reason your meal is not over at 9:00, they allow you to get up and go stand at the back of the other room (they dim the lights & pipe in the music...the view is not great from standing at the back of the room, b
ut better than no view at all.) Chances are you would be done well before 9:00 unless you deliberately stretch it out...Disney restaurants are more apt to get you in & out in 45-60 minutes.