We didn't work on a budget as such for after baby. We bought everything we needed while I was still working, so that when we were reduced to one income, we wouldn't have any of the big things to buy. Then, as often as I could, I'd buy a gift voucher for Target or Kmart and put it away. So once baby was born, we'd have some fall back vouchers for clothes and things for her. Worked really well for us. We made sure we didn't buy any until we were along in the pregnancy, so the vouchers wouldn't expire before they were needed.

All the best!