I respectfully disagree with the suggestion to arrive "late" at the port "because all you do is wait."
We like to arrive around 11am. It takes some time to get checked in. There is a enough to do to keep you entertained until boarding. The terminal is beautiful, there is a map of the bahamas, the model of the ship, the real ship is outside, there are Mickey cartoons on the many tv's throughout the terminal. Oh yea, the characters show up in the terminal too.
It's better to stand and wait outside (the ship or the parks) and then be able to cruise through any short lines you need to be in on the ship.
Don't eat a huge breakfast, the embarkation lunch buffett is wonderful and is a taste of things to come.