Announcing pregnancy?

When did you announce your pregnancy? Or when do you think is a good time to announce it? I'm almost 8 weeks and I think we're going to announce within the next few days, but I don't know if we should do it yet because I'm high risk. I already went to see my doctor and they did an ultrasound and everything looked good. It's just so hard to keep it from everyone lol. I've told close family and close friends, but the rest of my family and friends don't know yet. So I'm thinking about posting it to Facebook. Any advice?