We have done this with great success! We had an 8:15 and got to the gates at EPCoT at about 7:20ish. We were one of the first families in line. We were allowed to enter about 25 minutes later. We went right to the restaurant and were seated almost immediately. We ate our breakfast (not at all rushing) and managed to still ride Soarin' twice before people were arriving to get in line.
Good luck!