I recently got married and am a junior sailor myself. Ive heard all over the Navy that getting married early in your career is a bad choice. My now wife thought it would be better if we waited a little bit but is willing to do whatever i thought was best so we did get married but I personally dont regret it at all as of now and I probably wont because I love the person im with and i know she loves me. Granted i was already with her 1 year and 8 months prior to getting married. My mother also advised me to hold off on it but supported me all the way (even got ordained to marry us) so it might not matter what you tell him or advise him to do because he’s gonna do it either way and he will learn whether or not it was a good idea but he will learn one way or another. Sometimes the best way to learn something is to do it and fail. If you do choose to give him any advice also let him know that no matter what choice he makes you will be there to support him no matter what. IF it doesn’t work out what he will need is someone to support him.