The buses start running to AK about 6:30-6:45. For a tour at 8:30, I would be out at the AK bus stop by 7:00-7:15. The buses don't quite as frequently as the regular buses do.....at best, every 20-25mins. So, if you arrive at the stop as the bus is pulling away, you may face a longish wait. Better to ere on the side of being too early.