My thoughts (just based on reading these boards last year!) are that there's probably a very low chance of getting a TWE before March, if you're concerned that you'll make the travel plans and then get one. Even if by some chance that were to happen, it would still be possible to do the CVW as a possible motivator to pursue application next year. We did meet other parents at our CVW whose son hadn't received a nomination from any of his sources - which of course Navy couldn't know yet when they invited him to the CVW. So although the candidate was evidently a bit dismayed to be attending, I think it made him a lot more determined to try again next year.
However, most likely between now and then, your candidate may either get an appointment or still be waiting. Obviously in either of these cases, a visit and a chance to talk to admissions and see the academy and ask questions would certainly be worthwhile!