Some people start leaking earlier than others. I noticed leaking at 4 months but by the end i would wake up with my entire top soaked. My little girl is breastfed and 21 days old and I STILL even with huge breast pads on leak through my bra, pad, shirt and often soak my sheets too.
Just to add to the advise above, I have been leaking off and on from about 3 months. I am lucky that it is not continuouse, but it will ge worse the closer you get to the end of the preganncy.
if you have intercourse and your husband happens to enjoy some nipple fun, he might also notice that it comes out more if he *****, so just worn him about this, as some men get quite a fright, and some men enjoy (as my husndband) it and some will then rather stay away from that area.