Strictly no other outside food other than breast milk. Its pretty serious. Usually mothers start secreting the milk only when the baby suckles. The more the baby suckles the more the mother produces milk. So let the child suck even if you feel nothing is coming out. Secondly when do you know that your child is not getting adequate feed is when the child is unconsolable even after a feed. You can be pretty sure that the baby is getting adequate feed if he/she has a good sleep of atlest 1-2 hours after every feed and passes motion some 5-6 times a day. If you do notice any deviations from what I said,then go to your obstetrician who will clinically evaluate and then rarely if needed advice supplementary feeds. Without a doctors prescription pls do not give anything "even water" for the first 6 months