Super thick hair at 21-22. First noticed (admitted) my balding at 27. Actually I'd day I noticed earlier (maybe 23-24 that my hair was getting thinner, but didn't think anything of it or was in denial. I always had a very high forehead so I just convinced myself that was normal when my hairline was receding. I didn't help that I had long hair and always wore it down so that even to me, my hairline was rarely visible.
By the time I started treatment (just turned 27) I had thinned a lot, you could see my scalp through my hair at points and everything felt super thin. My biggest regret was not realising/admitting sooner, but I had a lot of other things in my life that distracted me. I'm 29 now, I regained significant amount of hair, I can style it the way I like, more or less, but I have to cover my temples with bangs to look good. My hairline and temples are ****, technically NW2, but not that nice round NW2, rather a forelock wedge that sharply drops off to my temples, taking the outer edge of my hairline too. I'd even rather have that widow's peak. One month ago I started applying minoxidil twice a day rather than once. I'm hoping it will make some difference to my uneven hairline and bald temples, not expecting miracles though.
Considering trying 10-15% minoxidil too, see if that improves things