When do boobs start leaking?


I’m 12 weeks today according to this app, I have my first scan tomorrow! I have both my nipples pierced and they are quite sore to touch at the moment not too bad though! I just wanting to know at what point in pregnancy do boobs start to leak as I really don’t want to take my piercings out till I have given birth and start breast feeding but I don’t really want leaking boobs cause I have big holes in them? Anyone had or has the same problem?