I am 19. Shall I take a year off
It really depends on what you want to do. If you're planning on spending your career as a successful attorney, and you just happen to be young, then I'd probably say "Yes, you should take a year off." If, on the other hand, you plan to follow in the footsteps of some of the better-known alumni from HLS and eventually have biographies written about you, then there's no need to wait. You'll probably want to have a little law-firm experience before you become a member of parliament or whatever they have where you're from, but you're better off having that experience after you get your JD.
So, basically, if you plan on changing the world, then GO. Do it. Don't wait. The earlier you start, the more difference you can make.