The Maitre 'd is always available on embarkation day, usually from 12:30 or so, just for requests like yours. We ALWAYS go to the dining room, and check our table assignment,,for just the opposite reason than yours. We enjoy the others at our table, and always ask for a large table. If that isn't what we've been assigned, then the Maitre 'd is right there, to take your request, and more often than not, fix it right then, and there.
Have a GREAT cruise, and enjoy that table for two!