OP - you should watch it from 1-6, because it sounds like you've seen it before. That actually makes for a more satisfying experience I find, as you already know everything so seeing it unfold in chronological order makes sense.
If you haven't seen them before, it is absolutely essential that you do not watch 1, 2 and 3 first. I'm not talking about any machete order or whatnot, that is fine. Those of you who introduce people to Star Wars by showing them 1, 2, and 3 first, are awful, awful human beings and there is a special level of hell waiting for you.