I'm 8 weeks and 2 days.. & i still haven't told any one...
I waited till about 12 weeks
I did it after I got the confirmation from the doctor. I have all close friends and family on there so if I miscarried they were my support as well and so I had nothing to hide.
14 weeks, after our first ultrasound showed that everything was going well. I miscarried at 11 weeks with my second and was very glad I hadn't told everyone yet. Whether it's "safe" to post? That's up to you. Superstition wasn't my concern, personal privacy was.
I did at 4 weeks. Miscarriage never seemed like a factor to me.
I told with my first on April fool's day, so it was a good month before everyone believed me! But I was only seven weeks at the time. This time I'm ten weeks and only family and a few close friends know.