Currently, if you are a JROTC student...the magic number is three years. If you complete 3 years of JROTC, your senior instructor fills out whichever document the recruiter requires (I fill out an AF Certificate of Training Completion") and also, usually, writes a letter recommending that the JROTC member be enlisted at the higher grade as specified in that services regulations/instructions. I work with the recruiter to make certain we dot the i's and cross the t's.
Currently, if you enlist in the USAF or USN with 3 or 4 years of JROTC satisfactorily completed, you will enter as an E-3. The USA and USMC only offer E-2.
Steve
USAFA ALO
USAFA '83