We booked for 7:10. We wanted a window seat, we had 7 guests in our party. We arrived at 7, and told the hostess that we would wait however long we needed to get a window. We were seated around 7:50.
We got our window seat which was nice, but in all reality to watch the fireworks most people head out to the balcony/veranda area. Getting a window is not imperative so I wouldn't bother.
If you take whatever seat in the house, I'd book it for 7:30. That way you are leaving about 20 minutes to get a table and then another hour or so before Wishes. By that time you will most likely be around dessert. Going out after dinner is the best IMO.