January 26 at AoA when we were waiting for a HS bus at shortly after 6, there was a MK bus already on a 9 AM opening day.
So buses start earlier than they advertise.
I would try to be at the bus stop at 6:45 so you are there, through security, and lined up at the gate by the time they open it at 7:45. Head down Main Street and toward the right near the castle if you want to be pretty much by yourself by the castle. Get a few pics, then head to breakfast. That's what worked for us.