We are cruising in December with NCL, and our cruise leaves at 8 pm. We're still not sure of our flight times (they were booked through NCL, and we won't find out until 3 weeks before) but what should we do if we arrive really early? What time can we get on the ship?
I can't believe nobody answered this for you, I'm a newbie and haven't even had my first cruise yet, but I can pass on the info given to me. Most of the cruiselines begin boarding a few hours before you actually are required to be on the ship. If you leave at 8 and they have assigned you to a 6:00 boarding time, I'm sure if you got there at 4 or 5 you wouldn't have to wait too long or perhaps not at all.
But if you got there super early, say late morning or early afternoon, you can get in the way of the departing passengers from the previous cruise. In that case you can go off somewhere on your own or take advantage of the precruise excursions like a nice lunch or a city tour. Depending on the size of the cruise terminal; you might even be able to check your luggage. The port your embarking from should have info on the amenities they offer independent from the cruiselines. And NCL's webpage might have the info as well.