The amount that BA want from each group is fixed - it has already been stated. The time period over which those savings are required is fixed and has been stated. Delaying does not change either of these, indeed it just means that the savings will be recouped over an ever reducing time period - they will be more severe.
Indeed, you are correct. The overall savings are fixed, but delaying those savings would mean that the action has to be more drastic as they would occur over a shorter time period.
That is what I meant when I rather inarticulately wrote "we have exactly what us CC are now facing - higher savings to be made because we were tardy in agreeing.".
