I started leaking at around 17 weeks. So much that it got my hubby wet while we cuddled in bed. He thought it was funny. Now at 30 weeks, I dont need pads but if I push on my breast it shoots colostrum like a cows teet. Kinda ridiculous.
In my first pregnancy, my breasts started to leak at 20wks. Everything was fine. I knew of others who leaked in the second trimester too. Just stock up on the breastpads lol :)
It's very common im 38+1 and I haven't experienced it yet