You just ask to schedule a comissioning physical. And yes you will need to fast for 12 hours prior. Females need to make sure they have a current Pap also.
For Aviation Applicants make sure you check out this link:
http://www.med.navy.mil/sites/navme...cuments/Waiver Guide - Physical Standards.pdf
Pay particular attention to 1.22 Applicant Checklist. It breaks it down barney style of who needs what. As with everytrhing in this process make sure you educate yourself on the requirements because no one cares about this as much as you do. Take charge of your own destiny!
Feel free to ask me any physical questions, I am an HMC and also an Aviation Medicine Technician (AVT). I used to work at NAMI in the office that reviews all of the flight physicals for the fleet. I was one of the reviewers, plus if I don't know I still have friends over there who will know the answer an I will find out for you.