If it's an EMH morning and you have 8:05 ADRs, you should be allowed into the park about 15 mins before the park opens, but not much more than that.
I seldom book early morning ADRs on EMH mornings...it almost seems a waste to me. I would much rather get into the park and do stuff for a few hours and then eat around 10:30ish...which is why I can't be absolutely certain as to what time you can get in on an EMH morning.