I would do 8:35 pm and grab a fireworks viewing spot in the hub to the left of the castle so you can get to Skipper after the fireworks - the show is about 20 minutes, so that will give you time to get to the restaurant. There is no guarantee you will even be out of Skipper's if you go at 7 pm.
8:35. I don't want to feel like I have to rush through a meal to get to something.
Also, we have had times where we have needed to wait to be seated there. So 7 might be seated at 7:15 or later.