Don't know if this helps. A SNCO Techie at Lyneham was told 6 months for his PVR but got out in less than a month.
I believe that the factor was that he had a definite job offer, in writing, including start date.
I know also that he was going through a divorce and needed the change (gratuity) to sort out his finances. Don't know how much difference this made though.
I think this has been done before on Pprune