The other major advantage to Universal, is they don't have a rope drop like Disney. Instead, you line up at the gate, and when the park opens, you can go on the rides immediately. So your position at the gate plays a huge role in getting walk on rides. At Disney it helps to be near the front of the rope for the walk back to the first ride. But you only get one or two walk on rides and then the advantage is gone.
Disney attractions have pre-shows that can make your wait in line go for 20-30 minutes. Most attractions at IOA don't have a pre-show, so you can walk right on to the ride and go many times.
The crowds show up at 11am, it's like a herd of people on the moving walking leading into City Walk.
Get to the parking garage at 07:45am, park your car, and get to the gate first. Many people are following this advice, so you'll actually see lines at the gate by 08:15am. By 08:30am, the line goes to the ticket booth. If you are first into the park, you have it all to yourself for 2 hours. This is enough time to take a lap around IOA.
In the summer time, or spring break, they open at 08:30am, but don't tell anyone. It just happens.
