Breastfeeding mamas

I'm 33 weeks pregnant and I've quit smoking during this pregnancy. Once I have he baby I would like to start again. It helps with my migraines and my anxiety.
However, I do plan on breastfeeding. Should I hold off on smoking until we are done breastfeeding? Only do it once in a while? I've read that thc will get into the breast milk..but I know that there aren't much studies done.. 
What have you mamas done?