A ball park figure of 800 hrs a year, over 9 years, equals 7200hrs. I'm guessing anyone with this amount of time would be well on their way to a captains job?
My understanding is that airlines have a SFO for long haul flights to provide rest periods for the Captain and FO. My guess is that these positions are hard to fill so Virgin has launched this programme to fill in the gaps and also lower their costs of manning 3 pilots to all long haul flights. SFO positions will be hard to fill as you're never in control during take off and landing and also most airlines do not count SFO hours.
Could be wrong but i imagine once starting with Virgin you'll be a SFO for a few years filling in those gaps until a FO position opens up and then you will start with 0 hours. This is risky as normally the min requirement for applying with other airlines is 1,500 hours and you may not reach that for many years.