Because the buses share a road with the start of the race, no buses will leave after the 5K until everyone has cleared that part of the course, which is usually about 6:30am. AK does have an early entry for on-site guests at 7:30am, so buses will be running from the resorts by 7 if not sooner. If you finish fast and are in a hurry and trying to make that early entry, you could take a rideshare and probably beat the buses back to your resort. Their pickup is on the opposite side of the finish area from the buses, so they won't have to wait for the runners to clear.