When to announce?!

So I'm waiting for my second round of blood work results, should know if they double tomorrow. I'm 4 weeks 5 days according to this app. Today my brother and sister in law just announced they are pregnant (she is 13 weeks). I can't wait that long! My first pregnancy we told them at 5 weeks but than it ended in a miscarriage, so I'm trying to decide when to tell my husbands family (mine already knows I can't keep secrets from them.) any suggestions?!? I'm so excited to be pregnant with my sister in law I can hardly handle it!