Only a little amount of milk is secreted for 2-3 days after delivery, but usually within 1-2 weeks enough milk is produced to feed your baby. Breast milk may not be sufficient at first, but it improves as the galactic hormones are excreted by the stimulus of baby’s sucking. If formula is given early, the baby gets accustomed to the nursing bottle and does not suck the breast hard enough. If the breast milk is insufficient even 4-6 days after delivery, you may add formula. However, at this stage you should consult your health care professional.