MK buses start running by 6:30, sometimes 6:15. For a 7:30 ADR, at CM's, I would be out at the bus stop no later than 6:40..these buses tend to arrive less frequently than the regular park buses do and if the MK bus is pulling away as you get there, you may not get another one for 20 or so mins.
When you get on the bus ask the driver which is quicker getting to CM's...the monorail or by foot. He may offer to drop you there directly, rather than have you hoof it over via the sidewalk. But, there's no way of telling if they can drop you there..so plan on walking (about 8 mins).
Otherwise, get a cab at about 7:00.