I was in a similar spot at the beginning of my transition. Visible M and thinning up to a few inches back. I am now just over a year on HRT and my hairline has improved significantly. I still have the M, but its much less pronounced and the thin parts are filling back in nicely.
I also had major dysphoria about my hairline, but now its way better and I barely think about it anymore. The way it works as far as I understand is that damaged hair follicles will repair themselves but destroyed follicles will stay destroyed. When you start T blockers the damage should stop getting worse right away and then begin to recover slowly over time.
Beautiful, delicate, and somewhat explosive!