Because the same bus usually does not make back and forth loops between the same given park and the same given resort, there are some legs (notably from a park to a neaxxxx correction, distant resort) that have little or no scheduled early morning service.
A CM should be monitoring the park bus platform and manually dispatching buses as needed,. Going through the motions of asking about a desired bus trip or route might get a park to park bus brought out or will help jog his memory if he forgets or overlooks something else.
At worst, if it is that long a time before the desired park opens, take a bus back to a resort and transfer to a bus for the desired park.