Assuming non-pregnancy. If a woman does everything to start lactating ex nihilo: taking hormones, drinking red clover tea, using a breast pump to simulating the baby sucking, etc. If all that is being done, how quickly would a woman start producing milk?
Would the purpose be to provide breast milk for a baby when substitutes won’t do? I just mention that because of recent formula shortages where means of obtaining more breast milk were discussed as a solution in some cases.
From breastfeeding-magazine.com:
Be patient, lactation without pregnancy takes time. Some women who have lactated before report that it takes about 3 days to a week to relactate. (It usually depends on how long it has been since you stopped nursing.) Women who have never produced milk before report an average time of two-weeks to a few months for changes to occur.
No baby/pregnancy so if we need a scenario above medical curiosity, let’s say she wants to get a job as a wet nurse.
Not human related, but one of my dogs had a step mom (a Rhodesian Ridgeback) who began auto-lactating and raised 9 puppies when their actual birth mom (a German Pointer) was disinterested (first litter, perhaps, could be the reason) and declined to be a parent.