I do recommend you give it a try. I was in a similar situation as you, although I made the conscious decision to teach myself "proper" typing when I was in my mid-20s. I don't think it has made my typing significantly faster -- maybe a little bit faster, with a bit fewer mistakes -- but I really felt the difference in how pleasant typing felt. Reducing my hand movements during typing has probably saved me from early joint / carpal tunnel / whatever problems.
I’ve probably been lucky in that I haven’t had any wrist pain and don’t really find typing uncomfortable but I’ll give it another try. I’ve tried twice before and didn’t stick with it.
It didn't take long, but I really forced myself to do all typing in the "proper" way. I would say two weeks at most, maybe four until it really sank in indefinitely. Obviously this is with a lot of typing, and you do need the luxury to be able to suffer through a few slow days.
