I'm 18, and i've been on T for a little over 7 months.
I started losing my hair at 6 months. A LOT came out in the shower, and when i dried off my hair. Luckily, i have really thick curly hair! I think it was just my hairline changing. It receded into a more male pattern. I wouldn't say that i'm balding per se, but my hairline has definitely shifted. It has a V shape now, but it's very slight and not really noticeable unless i pull my hair back. I just went through this month where i shed a lot of hair! The amount of hair loss seems to be back to normal now.
I think a big part of all the balding concerns on T, is that many transmen start T when they are upwards of 30. That's a normal age for hair loss and thinning, so when a transman goes on T, he'll lose a ton of hair at once, as his body catches up to what it would have been had he been biologically male. I don't think going on T causes any more hair loss than what would happen had you been biologically male. It's a much more gradual process for cismen, and i think it's pretty shocking for some transmen to lose all that hair at once!
If it makes you feel any better, i know a few ftms who have been on T for years, and still have a completely full heads of hair. Of course, they are younger guys in their 20's. haha who knows what'll happen when they hit middle age

. Matt Kailey is pretty well known in the trans community, and he still has all his hair. He's been on T for over 10 years (i can't remember the exact number), and Balian Buschbaum too. I think it probably has less to do with how long they've been on T, and more to do with their age. I dunno, it does seem like a disproportionate number of older transmen experience hair loss. Maybe it has something to do with increased levels of DHT (compared to cismen)? I really don't know.