4
It took my husband six months, but my FWB still spots and he’s been on T for four years now, so the answer is “it depends”
mine stopped after about 6 months and it hasn't come back in the 5 years i've been on it but it's different for everyone
mine stopped after a month or two i’m pretty sure. so you can see it’s REALLY varied
T + IUD combo took care of that for me