I wannna say it took me about 2 years of chewing at that tune before it sounded like it should.
It was like learning the F chord. One day you say, "When did I start to do this good?".
Once you get good with that technique, though, you can apply it to other tunes. It works good on tunes with simpler melodies. I use it for Silent Night, Autumn Leaves, and Beautiful Love.
I learned it on a nylon string but I've played it on a tele and an old Gretsch.
I play alot of fingerstyle stuff. I keep my nails shorter than alot of other players in that style(I think). I use the flesh backed up with some nail, if that makes sense to you. Using the flesh gives you a nice, round tone. I've heard people with really long nails play and it sounds too clickety- clackety for my taste.