How long is it to get R.N.

Good question before starting any endeavor. I'm not a nurse, but I know several nurses and nursing students. It takes a two-year degree for CNA and a four-year degree for RN.

I don't know if any of your job corps experience can be used directly for credit, but if it's nursing related, try and find out from a college counselor. If there is a chance that some experience might apply, I suggest you keep a diary of your nursing related experience, and try and get one of your adult leaders to initial or sign the pages periodically just as an acknowledgment that you did the work. I doubt a professor would accept just your diary, but you might be able to challenge a class (usually you just take the final exam) and get credit without attending the class.

Have fun and good luck.