Telling the boss?

Looking for advice on telling my boss I am expecting. The kicker is I have a new job that I start a week from tomorrow (the 11th). I'll be 10 weeks when I start and would like to wait a few weeks before I talk with him. I work in a high level, professional field. Anyone have experiences they are willing to share? Things that worked and things that didn't? 
PS - first trimester has been pretty easy, so I'm not too worried about having obvious symptoms. Thanks!