I agree that CV-17 will not be at "full operational capability" when it is commissioned in (probably) 2019, but the subsequent "warm-up" period is difficult to assess and quantify. Hence, I would prefer to stick with the commissioning date as a definite milestone that provides a clear basis for comparison going forward.
I would also expect CV-17 to "warm up" significantly faster than CV-16. PLAN is undoubtedly far better prepared for CV-17 in terms of institutional and logistical support, training regimens, etc. than it was for CV-16. Additionally, I would expect PLAN to make direct use of trained crew, pilots, etc. from CV-16 in crewing CV-17. The resulting inconsistency in the length of the "warm-up" period is one of the reasons I prefer to stick with the commissioning date.