I managed to go in 6 months on PVR (Engineer - 40) however, PMA stated minimum 12 months. Had to get a letter from chain of command stating that they could run light without me (obviously irreplaceable then!). Also, had firm written job offer, which was a PMA requirement to even consider it. Once that was sorted, PMA couldn't be more helpful. PVR'd in Mar, took off uniform in Jun, started new job at start of Sept, out by end Sept.
Have heard many instances of chain of command not being so understanding though and guys have lost good job offers because they could not get out quick enough. It would be interesting to know of individuals challenging the system and succeeding, as there are a few people I know of who are in similar situation and not being fully supported.