One exception to the prep school. GENERALLY, ALL enlisted military who apply to the academy WILL ATTEND the Prep School first. Usually, the only time the academy lets enlisted go straight to the academy and bypass the prep school, is if A) The are on the LAST ADMISSION Cycle and they will be too old to attend the academy if they wait a year by going to the prep school; or B) If the individual has been involved heavily in college courses WHILE ENLISTED and is in the "Academic Mode" in the academy's opinion. But normally; all enlisted applicants to the academy WILL attend the prep school first. Not much of a choice. Matter of fact; that is one of the PRIME REASONS the prep school was started. Was FOR Enlisted applicants wanting to go to the academy and become commissioned officers.
As for the original poster; I normally don't reply to a poster with only 1 post. "Don't know if it's a legit question, troll, etc". But in this case, the bottom line is you will be too old to apply to the academy. Unless you are applying NOW, TODAY, with nominations, etc. and received an appointment this spring, you will be too old. Your only other course for commissioning is to apply to ROTC; you can do this while enlisted; or finish your degree on your own, and apply for commissioning through OTS/OCS. But for you, the academy is NOT an option.