After how long can go into the pool after nipple piercing?

Months: Infection can go into the tissue of the breast and has a lot of space to travel. Healing takes months but it's an area you cannot examine yourself so you kind of need to get cleared for swimming at 2 to 4 months

Swimming: if the area around the piercing not show any redness, swelling, pain then you can enter the pool; if redness, pain or any type of discharge is present until they resolve, if they do not then see your doctor for a possible infection

Once fully healed: can take 9 to 12 months.