Depends on what you want to do, and if you want to be one of the first people in the park. On 9/21, when the parks open at 8, with 7am EE, I arrived with my daughter at 7:09, and we were the only ones there. It was too early -- security didn't show up until close to 7:30am, so we had to go back past security and wait for them. We did end up in the front of our line, and were on the first Nemo sub (but we had to RUN fast to get over to Nemo once the park opened).
I suspect that when EE is later, then more people show up earlier. I think in almost all cases you will be close to the front of the line if you arrive at 40 minutes before opening, and still in good shape if you arrive at 30 minutes prior (but you won't be first in line). If you aren't planning to go on Nemo, then arriving even slightly later will probably be fine, since most people right now who go early are trying to get over to Nemo.
-Bret