N.D.
With my first baby I was in maternity clothes at about 5-6 months, with my second it was more like 3 months (maybe earlier but it was 5 years ago) and with baby #3 I am sure that I had to pull out those old clothes WAY before I even knew I was pregnant :) I think you stomach muscle relax a bit with each pregnancy no matter how many sit ups you do and there for that baby in there will demand all that space much sooner then the olds sibling did. Just enjoy being prgnant no matter how soon you take out those maternity clothes, its the only time in you life here on Earth that you will get to assist God in a miracle! Congrats to you and your family on the newest addition!