When do you start telling people?

So far have told 2 friends, as they knew we were dealing with infertility issues, haven't told any other friends or family yet. Want to get a blood test next week to confirm and then will tell other friends. We will DF's sons in a couple of weeks - it's a bit tricky seeing as I teach at the school they attend so it'll be out in the open very quickly once they start sharing with friends, but I'd rather they know early rather than make them wait and possibly hear rumours through the school community (shockingly gossipy school).
It's nice to see I'm not the only person who struggles to keep it on the downlow till 12 weeks, don't know how people do it!

Last time we told most people after my scan at 6 weeks, this time we haven't told many people (family and a few close friends) and won't do til next scan, I've had a bit of bleeding and cramping so just want to make sure all ok. It's hard not telling people, i can't believe some people tell no one til 12 weeks that must be sooo hard!!