I'm currently 8w6d, 8w3d according to U/S and I'm waiting to tell anyone, hubby excluded, until the first trimester is over. I want to wait as long as possible. I told everyone when I was 5wks with my 1st and I lost her to Interrupted SIDS at 10.5wks, so I'm waiting as long as possible. I don't think I could handle everyone knowing if I lost 2 kids.
Tell people when you feel comfortable telling them, though it can be hard to keep it a secret if you start throwing up or showing early.