We told our parents and siblings around 8 weeks, only because I was still on my parent’s insurance and I needed to go into the doctor. We were very young and felt like keeping it private from the world for as long as possible, so we waited until we had our gender scan at 20 weeks to tell everyone else. No one knew we were pregnant until we announced on facebook that we were having a girl 
Next time, we plan on telling our family a little later (around 12 weeks), and then we will probably tell the world once we feel comfortable, possibly again after we know the gender. I am excited to a cute little announcement this time around!
My husband and I have decided not to tell anyone until we reach the second trimester. [name]Just[/name] in case. I have desperately wanted to tell the children, but DH has been adamant about not telling the kids in case they let it slip to his ex-wife. He really does not want her to know before we have had a chance to tell all of our family and friends (she has been known to have a rather large mouth). However, we are almost to that point and I cannot wait to see the reactions of the kids and our families.