The busses pick up at each resort: First is Sports, then Music, then Movies. Each resort has it's own bus stop at the front of the resort. When we were there in Sept, we were at the bus stop (Movies) about an hour before we wanted to be somewhere, and we were always early getting to the park. It would probably depend on the time of year, but an hour early was a little too early when we were there. The ride to the parks ranged from about 15-25 minutes after we got on the bus. The busses seemed to run fairly often, the worst bus for us to catch was Epcot, we had to wait about 20 minutes for that one day, the rest usually came about 10 minutes after we got to the bus stop at the most.
HTH, Steph