Everyone can enter the park at the same time. If you are eligible for EE, you will be able to proceed to Hogsmeade (or Diagon Alley / Minions for Studios). If you are not eligible, you can just hang out in the entrance & Seuss areas until close to official park opening time. You can grab breakfast, explore a bit, relax, hang towards the front of the "regular opening" crowd. There's not really much benefit of arriving at 8am if you don't have EE; you'll be in about the same position arriving at the gate at 8:30am and not have to wait for the EE crowd to get through the gates. They do tend to open 10-15min early so I would aim to be in the park for 8:40am but not much before that, earlier if you're grabbing breakfast. Gives you time to meander & take in the scenery in Port of Entry, avoids the crush of people lined up at 8am.
Only a few rides open during early entry. The rest of the rides, everyone is on equal footing. When the rest open, it also spreads out the incoming guests much more effectively. There will be an hour or so with nice short waits on most rides, particularly those that aren't near the entrances. Minions & sometimes Rip Ride Rocket are the exceptions - they see decent lines pretty quickly. Hagrids wait will be pretty much the longest of the day from the middle of EE through the first hour or so of regular opening. Pretty much everything else will be reasonable, except maybe Velocicoaster especially if Hagrids was down most of early entry.