Contract Programme - Access Dates

On an NEC 4 option A we have an agreed clause 31 programme included in our sub-contract, we also have a series of access dates with windows for commencement - between x and y.

If our agreed programme is delayed, but we are within the parameters of our access dates to we have grounds for a CE?

In essence which takes precedence our agreed clause 31 programme or the access dates included in contract data part 1?