I will be 12 weeks tomorrow. We have told close friends and family but not everyone. I wanted to take a cute announcement picture tomorrow and let everyone else know but I haven't had my first US yet. That will take place on Dec. 10. Should I wait until after that to announce it? I'm just terrified something will be wrong at my US.
Re: Good or bad idea?
Short answer: it's up to you. If something does happen, some people like having the outside support.
If it makes you feel better, my next US is Dec 9 (for the anatomy scan) and I'm right there hoping time flies also!
And in reference to your mom, in no way does your announcing or not announcing early have any impact on whether you miscarry (I assume that's what she means by "bad luck"). That has a very blame-y feeling to it. It isn't bad luck. They have no bearing on each other.