If you have Gynecomastia, I don't see it, at least yet. It usually take at least three months on something like finasteride . On the other hand, shaving the torso has a tendency to make it look more feminine to me. so shaving, waxing, sugaring, or whatever is something I would not do.
Did you also notice that loss of libido and sexual function is also a rare side effect of Finasteride? Not as common as Gynecomastia, but still on the list. It seems that if you want the hairline of a 12 year old you might have to accept the sex life of a 12 year old too.