It depends on the person, but in general, I rarely see 18-year-olds make it through and get selected. I would say mostly because of their lack of maturity in adverse situations. That being said, I would recommend you take care of anything you need to in order to be able to make your career in the Air Force your main goal. Then come in.

It really depends on what your current fitness level is, however, generally speaking I tell guys who are modestly in shape to give themselves at least 8 months to get ready.