How bad is it?

[anarki]

Hi, I'm a 36 yo guy. My temples started receding about 10 years ago. What worries me is the thinning at the top which I've noticed about a week ago (probably started much earlier, I just haven't seen it). I don't want a horseshoe in 3 years
Is it worth start taking finasteride now to at least maintain this stage, or is it too late?
(I had a 9mm buzzcut about a month ago.)