I started it at about 36 for anti aging. Still using it. For aging it cant be beat.
I just turned 39. I will stay on as long as I can afford it. I do mix in peptides peroidically, and take a month off a couple times a year to keep it effective.
Plus one to just about all of that.
I don't know if my hormone levels were lower than others my ago (38), but I noticed an immediate improvement mentally, with sleep, and with recovery (and of course fat loss, but that's not much of a concern for me). I can't imagine ever being off it for an extended period now.