I started leaking colostrum but my doc said not to pump. Just hand express if it gets to be too much. The great thing is that your body replenishes what you push out so no need to worry about running out.
Your actual milk won't come in till a few days after you give birth and you should wait a few weeks before pumping otherwise you put yourself at risk of over supply.
Mine didn't come till after I had my baby my last pregnancy and my friend started leaking and everything when she was bout 20-21 weeks and she's almost 30 weeks now . Everyone's different .
The actual milk doesn't come in until after the baby is born what you get when your pregnant is colostrum which is your babies first food you won't need to pump before you give birth
Recent information I've read (from WIC) encourages you to wait until 6 weeks after baby is born to start breast pumping. They say otherwise it interfers with milk production and bonding with baby since they'll prefer the bottle over your own breasts.
I never started until after my babies we're born.
Its different for everyone. Most dont start until after the baby is born