From my own experience with PVR I was straight with both my Boss's and my Desk Officer and they were very good for me. The line was generally if you had an offer of employment then the RAF generally wouldn't stand in your way - subject to the service need.
The bummer was always they couldn't tell you how long for your PVR until you'd PVR'd, but you don't want to PVR until you know how much time it will take as this will affect your job offer and the loop goes on.
My advice is just be straight with Bosses and deskies and, unless you've got a berk for either, then they'll be straight for you. My Deskie has already told me I left at the right time and he keeps my number in case he needs a rec for a job.