After pregnancy and giving birth to the baby your milk should begin to regulate within 6 to 12 weeks.
After 12 weeks the breast milk supply should be fully or nearly fully regulated.
After your breast milk regulates you should notice your breasts begin to feel less full, soft, or even empty which is normal as your breasts milk supply regulates.
However for some mothers that may have an oversupply of the milk it can take around 14 to 15 weeks for the breast milk to regulate.
But usually for most people the breast milk supply is regulating or regulated fully within the 12 weeks.