7:30 at the absolute latest. Earlier than that to be safe. We arrived at 7:30 last year and were toward the front of the line for signups. We were able to pick our way through the crowd and get right at the front on the left side to watch the Stormtroopers put on their little pre-opening show, so we were at the front of the JTA stampede when the internal rope dropped and got our choice of shows.