mine came when i was 8 months pregnant with my first.. at first it felt weird coz i was in the office then i felt my shirt got wet.. it was embarassing.. i then had to use breast pads..(which i think was too early).. so after giving birth, my daughter was so happy with all the milk she can get.. after giving birth though, i just had the yellow thing(colostrum) which was so hard to suck( by the baby of course..lol)..after a few days it was just overflowing.. when i pump i can fill up 16 oz.. my baby would always finish it up.. stopped breastfeeding on her 6th month coz i had work..
Its already developing. If you squeeze, you probably see some clear liquid come out. But breast milk will fully arrive within hours after giving birth. And it will continue to come depending on the amount you use.
Couple days or less after giving birth