we try to board as early as they will let us because the cruise starts the second you board the ship and it seems to make it last longer..
macmom, I'm the same way!
Usually I try to get there if driving around 10:45 to get the luggage dropped off and the car parked. Then in line by 11 or so. This did cause a problem once in Port Canaveral when the Elation came in late during a repositioning cruise. We couldn't park until they could get the other cars out of the lot. It usually works out great though.
My ritual is to head for lunch on the Lido, then go meet the Lido bar manager and bartenders. Then off to explore the ship. By then the cabin is usually ready and I can drop off my carry on's and freshen up. Then back to Lido for a pre-muster libation.