This is the ONLY time I'd take the bus. IME it's never clear when the monorail/ferry starts running in the morning. Ideally I'd want to be at the MK gate 30-45 minutes before my scheduled ADR. You are pretty much stuck if the monorail and ferry aren't running that early, or if the monorail is running less-frequently because of the early hour. I'd try to be at my resort MK bus stop at least an hour prior to my ADR time (maybe more like 75 minutes... I stress about the things I cannot control!)