35L is an application MOS so he must apply and be accepted by the 35L recruiters. He'll most likely be rejected, lots of fully qualified applicants are rejected for one reason or another simply because the interviewing agent didn't like them. But if he is fully qualified and he interviews well, the proponent will send him an approval memo. Then he has to go to his S2 to start his Top Secret clearance. In 6-12 months when he gets his Interim TS he will then go to his Career Counselor who will do the reclass request and get a class seat. That seat will be 3-15 months away depending on availability. It's usually between 4-7 months. He will attend school in a TDY status enroute to his next duty station. He is not authorized to bring family with him to school. There are different options for TDY but unless he is going to Korea afterwards he will be authorized to return to your current base to clear and then move to your next duty station, or he can move you ahead of school to the next duty station.