I thought it was an hour and a half? Only because we have an 8 am PS at both Donald's Breakfastosauras and Crystal Palace during our trip, and I was told that we would not have to worry about arriving on time for them.
Dispatches for the buses start at 7:00am. Limited service is provided to the theme parks and resort areas for breakfasts. Full park service begins one hour prior to the park opening (including EE)