I just had my baby last Friday. The first 3 days were just colostrum (spelling?) and it came when the baby began to nurse. My milk came in 3 days after, it just sort of shows up without warning lol. I wasn't making enough to feed her (plus nursing was very painful for me so nursing was becoming near impossible) so I've started pumping and now I have a great supply (and I'm not in any pain) I pumped every 2 hours for 30 mins to an hour at a time (sometimes no milk would come so iI'd keep pumping until it'd finally start so a few times I pumped for 2 hours straight) and now after a few days I can produce up to 5 ounces in a session! It's just a matter of pushing yourself to do it, I was sooo close to caving and giving my daughter formula because it's honestly exhausting but I'm glad I've stuck to it. Don't stress out, your milk will come and if you aren't producing enough use a breast pump and the more you pump the more your body thinks it needs to produce.
Your actual milk won't come in until a few days after baby is born. In the mean time baby gets colostrum that you make. Usually colostrum doesn't leak out so some moms don't realize they have any
Most of the time milk doesn't come in til baby is born.