Vern:
Disney doesn't list its hours, however,
their policy is that buses typically begin running an hour before a park's opening. The monorail also follows
this same policy, however, monorail service between the Magic Kingdom resorts usually begins at 7 a.m. The boats serving Fort Wilderness follow different guidelines. The posted sign at the marina states that the boat for the Magic Kingdom departs a half-hour before park opening, yet, I have seen it leave earlier. However, you have another option.
Plan on taking the boat at the fort's marina that is headed to Wilderness Lodge and the Contemporary Hotel. Typically, these smaller water shuttles begin running as early as 6:45 a.m. Once you've arrived at the Contemporary, walk through its lobby and either take the escalators up to the resort monorail that should be running and on to the Magic Kingdom or continue walking out its front doors down the sidewalk to your right and cross the street and make the 10-minute walk over to the Magic Kingdom.
Wishing y'all a magical vacation!
Whitney