Be in line before seven. Exact time depends on how crowded it is the day you go. They typically close the line before seven. At that point, those in line still ride, but they try to have the ride closed as close to 7 as possible.
Wondering how long the wait will be. There are probably a lot of people leaving IOA via HE to catch the last two hours at US. Anyone have a guess as to what time we would get to US if we jumped on line to catch HE at 6:30 (again, assuming IOA is closing at 7 and US at 9)?