Hi. I can only speak for us. We try to get to the terminal at least 1 hour prior to when they say boarding starts. If they won't let you board, you should be able to stand in line. Trust me, the line can be verrrrrry long.
If you have nothing to do the day of the cruise, might as well go down early. Trust me, you won't be the only ones. I hope your cruise, and honeymoon is very special for you two. Best wishes