Your body will start to produce breast milk at about your 5th month of pregnancy. It's colostrum which is the 1st milk that your baby will obtain. It's very thick and rich and full of the amino globulin, full of vitamin A, but it does not come out pouring. It's very, very concentrated and so it's teaspoons worth it's not a lot but it gives your baby the best beginning and then by day 3, 4, 5 with constant stimulation a every two to three hours during the day of the feeding or pumping then your milk will start to transition over to more mature milk and that's when we feel the full breasts and the possible engorgement in the very beginning when you 1st deliver you're not going to feel an overwhelming amount of milk but it's the perfect amount for the baby.
On day one at birth the baby's stomach is only the size of a marble and by day three it's the size of a shooter marble, by day ten it's the size of a ping-pong ball. So the baby has taught your body how much to produce by nursing frequently and it will eventually even out to what the baby can take so the baby stomach expands so it will start to accept exactly how much what you're producing. Again you might feel that there's little bit of an overwhelming amount in the 1st couple of days that's very, very normal. But as your milk changes over from the colostrum phase to the more mature milk, you're bound to having a little bit of engorgement just because of the extra fluid.