BAH is purely based on rank and dependants. Current students get O1 BAH when you graduate O3 BAH. Amount depends on where you live. Since you will all be given PCS orders, your BAH will adjust to current rate at your locale.
All of this information can be found in the JFTR (Joint Finance and Travel Regulation) at
http://perdiem.hqda.pentagon.mil/perdiem/portalstatus.html.