Problem is, Thor, that most of the services won't do ASVAB/med and then DEP in at a later date. It's all one big ball. Are you saying they won't DEP in 11S for Air Force, only 12L (workforce)?
But you are correct--what's available is better in the winter months--SOMETIMES, based on ship date. Hate to tell you, but if he's going into a small field, you may not get him to ship right after graduation.
Navy and Marines are still doing DEP.
My son was in DEP for 8 months waiting for an opening for what he wanted to do.
My young friend has been in DEP for Marines since early last spring to ship Jan 4.
Unfortunately, she is no longer going through with it......she was "ruffied" the night of the Marine Ball at a bar afterwards and later arrested. Until that is resolved...she's SOL.
