If you have concerns about your seating arrangements, go to Dining Changes once you board. The location and time varies by ship, but check the navigator app once you're close enough to connect to onboard wifi (usually works once you're at the port). They can let you know if you have a private table or not (and maybe help get you one if you don't already have one).
Table numbers change cruise to cruise, as they will reconfigure tables, table sizes, etc. to accommodate different parties. So there's no way to know in advance.