My experience late last year..
Flying pay goes down from the date the PVR form is stamped at your handbrake house. Takes about 2 months for PMC to action this depending upon where you are in the pay cycle.
You have to pay the whole amount of the FRI back and then usually at the end of the tax year (but there are procedures to do it earlier) claim back the tax you paid when you received the FRI.
I made sure I PVR'd just one week outside my FRI window!!
