Hogwarts Express starting time

Going to Universal October 28 & 29. Studios opens at 8am, IOA at 9am. Is it worth doing the first hour at Studios then riding the HE over to IOA for "RD?" When does HE start running? Right at 9? Will that put me too far behind as far as maximizing RD?

Is there early entry that day? Think HE starts when both parks are open but could be wrong.