If at all possible, find another way to get to port so you can get on the ship earlier. My family and I always get to DCL by 10:30 or so and check in. We will wait in the terminal until they let us on. I believe around 12 or so. Then we hit the buffet and go to the pool. I think the buffet closes around 3. Usually there aren't very many people at the Mickey pool which is very nice. You will be able to get to your stateroom and organize or whatever. If this is your first cruise with Disney, it is fun just to look around the ship, register the kids, make Palo reservations, etc. If you take the bus you may arrive at 2:30, check in, and by the time you get to your stateroom it will be lifeboat drill time.
These are just some observations. Good luck with whatever you do and have a great time!!!