Tim, congratulations on completing your first draft!
As to your question: I think this is a very subjective thing. Depends really what you feel you need. Personally I am going to leave my draft for a few weeks, then read it through in one go as a reader would, making any notes to myself on the way. I think lots of obvious things will jump out at me when I do this. Then I'll go through the whole thing (maybe on a paper print out, maybe on computer)sorting everything out, and also challenging myself on every word so that it's as concise and clean as possible. If I hit anything that is a problem I'm not sure how to solve, I will post it here or share it with my novelists group for feedback. Only when it's as good as I can possibly make it will I start sending it to agents. I may also send the first three chapters and synopsis to Hilary Johnson or the Literary Consultancy. I probably won't share it with friends before I'm happy with it.
BTW, I've just ordered 'Self Editing for Fiction Writers
Second Edition)- How To Edit Yourself Into Print' by Rennie Browne.
Susiex
<Added>This smiley thing's getting to me now - where did that blue moon come from?!?