For a brand new flight surgery straight out of internship (that is what i am assuming you want)...
VSP: Done through finance. Should be automatic. 5K paid in monthly installments (416/month I think). make sure finance is getting you this, but it may take a couple months to go through.
ASP: 15K/year, paid in one lump sum. The application for this can be found on the knowledge exchange, under popular links click on medical special pays. The application needs to be signed by your med group commander. This pay commits to 1 more year from the date it is paid, so be careful about the timing that you take this for your last year of your GMO tour, as it may affect you when you can get out to go into residency.
Flight pay: Once you get your wings and an active 1042 (after you graduate from AMP), you hand your 1042 and physiology card (from your chamber flight) to base flight pay department. Then after you complete your first flight and it is recorded in AMS, your flight pay will start the following month.