C.F.
As for me, I didn't dive into weight loss until my second (and last) child was a whole year old and sleeping though the night...I needed to be sleeping well before I could sap my energy with calorie restriction. Not to mention, I wanted to be eating properly while breastfeeding. It was a long road (I had 40 extra pounds still left over from the pregnancies!...took a year to drop most of it) but if I'd tried dieting while still not sleeping through the night I would have had no patience at all for my poor kids. And yeah, I think it takes longer for us "older" moms too (I was 39 at birth #2).
Good luck, be kind to your bod and don't worry -- the time will come for dieting and exercise soon enough, you'll know when you can spare the effort. In the meantime and always, enjoy your kids! :)