A great many things can dictate when you tell those close to you that you're expecting. Here's what different people in different situations take into consideration.
You and your partner discovering you're pregnant is a special moment that you will likely remember for the rest of your lives. The only annoying thing about it is the belief that once you have found out your exciting news, you shouldn't tell anyone. That you have to wait until that sacred 12-week mark to break the news. Truth be told, it actually depends on your circumstances and ultimately what you want to do, as reported by Today's Parent.
The main reason parents-to-be don't want to announce their pregnancy until that 12-week milestone is due to the chance of miscarriage greatly decreasing after that. While that's true, there are also reasons to reveal the news before that time. If the baby is a result of successful IVF treatment, those close to you will likely know what you've been going through so it will be hard to hide it. The intense morning sickness some women will get will be hard to hide too.
As already mentioned, the chance of suffering a miscarriage drops off significantly once you hit that 12-week mark. Most parents also wait until this point to tell people the good news as it's when the mom-to-be will have her first scan. Not only will that give you a physical ultrasound to show people, but you will also know if there are any issues or problems with the baby.
Believe it or not, some people don't reveal the news that they have a baby on the way until well after the first trimester is over. That could be so they can know the sex of the baby before telling family and friends, or because they have lost a baby during pregnancy in the past and what to be 100% certain that everything is okay first. Or, perhaps you and your partner just like being the only ones who know.
Basically, despite what most people think, there is no right or wrong time to tell people that you're pregnant. While all of the above are reasons as to why some opt for certain times during pregnancy, none of the points are hard and fast rules, just advice. When it feels right, start to tell people. Plus, you don't have to tell everyone at once. Just make sure those you tell first can keep it to themselves.