Well, write them anyway. You'd be surprised how things can change over time. I went to book camp (Navy) and my family wrote me a lot. As did a bunch of my friends. Things to remember while going through boot. Work hard, listen, and learn. You are doing something for yourself, taking a step forward to serve. Learn the traditions, learn to be part of a team.
As a vet (even if I'm a Squid who likes to pick on Marines) I respect whatever decisions it took to make the commitment. Semper Fi!
(And remember if a squid picks on you.. it's because you're the guy they expect to protect them from the Army guys!)