FP+ for Wishes on Christmas eve

[castle4us]

My son really wants to do the FP+ viewing area on Christmas Eve. If they let people in one hour before Wishes (8:00), how much earlier would you guess we would have to line up. I'm assuming people would start lining up before 8:00. We have a 6:30 reservation to eat at the Plaza. I am trying to make a schedule for the day and was trying to see if I could fit in a ride with a FP+ for 7:30 when I am able to make my FP+'s.