From what I can remember, (and its going back a couple of years now!
) our room was not ready until 1.00 pm (which I think is why they state that time). We arrived at the port at about 12:00 noon and it took quite a while to book in, but then we were able to go on board before 1 pm (and we were certainly not the first!). We went for lunch at Topsider and explored the ship whilst waiting for the room to be available.
If you can get there early and board, then that is a great time to take photos as there are not so many people about. Have fun!
Don't forget to post a trip report when you get back. I am keen to hear if ther have been any changes.