Don't worry about it too much. The first real career milestone that has a soft "requirement" for a graduate degree is O5 command.
Definitely a "soft" requirement at this point, but certainly helps even the playing field. I know several, including myself, who screened for one of the command options (op, op-t, shore) without a Masters. But, like Brett said, way too far in the future to worry about at this point. Plenty of time to get it done if you want it. Focus on the wings and getting through your first squadron tour successfully.