How early can a girl start lactating without being pregnant?

Answer:
I am 18 years old and in a very active sexual relationship with my boyfriend. I want to know if I can lactate milk from my breasts as a sexual practice between him and myself.
First answer by Autumncoomber. Last edit by Autumncoomber. Contributor trust: 1 [recommend contributor recommended]. Question popularity: 2 [recommend question].