On really busy days, they open at 08:45am, and in the summer, they can open as early as 08:30am, but they'll never officially announce it. You just need to be standing there at the front of the gate. That's early entry to me. I go in first, and get my front seat ride on Hulk, back row ride, Spiderman, Dr. Doom, then high tail it to Deuling Dragons all before 9am. I'm serious, on days when the park has opened early like that, I've done Marvel Island before 9am.