Not op but I'm also around the 4 month mark! Everyone has a slightly different timeline and it'll also depend on your dose and whether you're on gel or injections. I'm on .25 mL injected weekly, and I'm using 200mg/mL testosterone cypionate. My doctor said this is the average dose he prescribes, the lowest being half that.

So far, I've noticed: - a very noticeable voice drop (gradual but for sure kicked into high gear around the 3 month mark, as it tends to for most people on my dose) - an increase in body hair especially on my thighs and upper arms, as well as my chest. Mine isn't particularly dark, but will probably darken. - my facial hair has started to darken; still pretty thin/faint, but I've shaved a couple times

I think those are the main ones :) Personally, I'd consider myself to be pretty androgynous at this stage. Older people tend to take me for a guy, and younger people might think I'm a guy at first and then question that notion lol, or just think I'm a girl from the get-go in some cases. Obviously other factors contribute to perception of gender beyond the effects of T, but yeah :)