G'day Steve J and welcome aboard!
You've started your posting here with a good question yet one which presupposes what is not written.
Let us address those suppositions first. Let me ask the question, why do you assume that each creative day was uniform in length? Where in the Genesis account does it state that?
I believe that even the WTS have come round to thinking that these "days" were periods of time of uncertain length. Yes, Fred Franz laid great emphasis on each day being 7,000 years but as has been commented by my fellow Australian they seem to be shying away from that in recent times. So, back to the periods of time. Why should they be equal in length? Just because we think it would be neat and tidy, or because we conjecture that since God is a "God of order" then it must be so, doesn't mean it was so, does it?
Indeed, many christian believers see no contradiction between Genesis account and evolution.
So, in summary, there is nothing to state ctegorically that each creative "day" was either uniform or 7,000 years in length.
Cheers, Ozzie