1) for me, t made my breasts/nipples less sensitive. i only noticed this when i went off t and started having a period again, bc those hormonal shifts made my breasts/nipples more sensitive/reactive. 2) i started feeling sensitivity two weeks in, and had noticeable to someone else bottom growth ~6 weeks. not a lot! but a difference. 3) facial hair relies on t, more specifically DHT. it can be encouraged by minoxidil or dht blockers can prevent/reduce it (but those also impact other effects).
i dont have an answer for #1, but for #2 i personally saw growth pretty early, around 2 ish months in on gel (for some it takes longer and it wasn't a whole lot) and for #3, it can draw on a ton of different things like genetics and t levels and such. some ppl don't get a ton of facial hair, some get a lot
for facial hair growth it’s primarily a function of long-term exposure and genetics. even among cis men, it can take 6-8 years for a beard to “mature.” some people just respond strongly and are genetically predisposed, like when you’re in high school and there are freshmen with beards.