In my time in the program(me) the UK IOC was 2012 and back then there was confidence that the USMC would achieve IOC well ahead of that date, so our date was driven by the UK funding profile. When the weight issues hit I was in one of the departments trying to keep-up and explain the almost daily slicing-off of core capabilities at IOC. Back then 2012 would have seen us with almost all the US weapons plus the UK requirement. It will take many years before we will see the capability originally envisaged for IOC.
It's funny that the F-35C articles have brought this topic up again as, from my perspective, the US Navy were by far the most intelligent, practical and pragmatic customers. They really have achieved the near-impossible from what was a compromised design starting point.
Oh and they managed to keep on friendly terms with LM too. Admittedly they did benefit from being the only customer of the F-35C, but they still achieved miracles given the hospital pass at the start of the program(me). Indeed, the overall F-35 program contains perhaps the worst defence design and procurement program and arguably one of the best too.