Patience is a virtue or is it?
I have to say it really depends on a number of things. I personally did not tell anyone until almost the end of my first trimester. And then we only told our parents. We waited until the end of the first trimester to tell the rest of our family and then just let the word get out as we told and other told.
First, it is such exciting news!! I think you need to discuss with you husband what he would like to do as well.
Second, I personally waited because I had a few friends who had miscarriages near the end of their first trimesters. This is not something that you really want to be thinking about, trust me I know, but I didn't want to have the world knowing and then god forbid something happen, ya know?
Third, like previous posters said, if you have horrible morning sickness you probably should let someone know. I was lucky in that I taught middle school and was conviently sick during class changes!
Finally, despite what I say and anyone else, do what is right for you! If you want to tell everyone, then shout it from the roof tops! Congratulations! This is an exciting time. My little one turns one in 2 weeks and it seems like yesterday when I took my pregnancy test!