Nominal IOC for USMC may be 2012 but they have already exteneded the OSD for AV8 out to 2024 - perhaps gives an idea for when they think Dave will be up and running. OSD for GR9 is stated in various places as 2018.
Can't see why it's a problem for Harriers to operate off CVF, you could embark 2 Harrier Sqns at once plus enough Merlin to keep nasty Iranian subs away, plus SK 7s plus a SAR cab or two without the chronic overcrowding currently experienced on CVS.
Alternatively put a decent force of Marines and Junglies to move them on board with a sqn of Harriers to provide CAS topcover and you have a very useful package. With a deck that size the possibilities open to you regards TAG allow the planners much more flex.