I've done cruises out of NYC twice, but on the Magic. One was over Thanksgiving and it was packed (my busiest cruise ever), the other was to Canada and not so full. I'd guess that moving from Magic to the Dream which is a larger ship, it'd take longer to fill up, but that's totally an uneducated guess. I'd wager they'll be busier around holidays. NY/NJ schools get the Jewish holidays off so there can be a lot of extra days off around Sept/Oct (don't know when they fall this year) which will probably see more people traveling.