"Balding is not a choice. Bald is a choice."
-Mystery, in The Game
I started going bald at age 20, and started actually showing it at 21. I procrastinated for years until this past year, when I finally grabbed a razor and shaved completely (up until then, I was buzzing shorter and shorter as I felt was needed). If you're having trouble going through with it, how I ended up doing it may help you. I signed up for a cancer fundraiser which shaved the heads of the participants. Why not kill two birds with one stone? I wanted to support a good cause, and shave my head too. This will allow you to, when showing off your newly shaved dome, say that you did it for a good cause and you like how it looks. This takes off some of the pressure and embarrassment that many people are afraid of when shaving their heads.
But, the main thing to remember is that your friends never liked you for your hair. You're the same person, just without hair. Big deal. Everyone gets dealt bad cards in life, yours happens to be hair (other people may have much worse problems that you can't see, and would take your cards over theirs if given the choice). Everyone will just want to feel it anyway, so why wait?