I personally think waiting out the first 3 months is a good idea (first trimester) , since miscarriages are more common. I know its hard holding it in especially when it your first pregnancy. I also think its' ok to go ahead & let your close family & friends know :)
It's different for everyone. I waited until 13 weeks to tell people with my first but started telling people a little earlier the second time
We wait until just before I start to show, not because of miscarriage, but because nine months is a long time, and I don't need anyone reminding me of that (plus with my first two, it was an additional two weeks)
It's a personal opinion, some people wait until the second trimester to pass the "miscarriage" stage, but I think that can happen at anytime honestly and it's a true blessing if it doesn't. But others don't wait either. It's a personal opinion. As soon as we got a positive we were telling our families.
Its recommended to wait to get through the first trimester. 11-13 weeks is usually the goal :)