First of all, congratulations!
Secondly - this is such a personal issue that there's no "right" or "wrong", but I just thought I'd share my experience...
I've had three pregnancies - the first, it took a year to conceive and then just when I started looking into fertility doctors etc, I fell pregnant naturally. I told everyone as soon as I knew and was happy doing so. I had a healthy, non-eventful pregnancy and a healthy baby girl at the end of it.
The second pregnancy, like the first, I told everyone right away and literally days later (less than a week) suffered a miscarriage. In theory, I liked that people were understanding and supportive - although I did feel a bit foolish having to "take back" my news right away.
The third pregnancy was just a few months after my miscarriage, and due to that, I decided to wait until 13 weeks this time. I announced my pregnancy right at 13 weeks, and again just a week later, we found out that we had complications in the pregnancy. At the time, it was very scary - we weren't sure what the outcome would be. In this pregnancy, I wished that I had told everyone sooner so that we could have celebrated the pregnancy before complications arose. My 2nd daughter was born with a rare form of dwarfism and is currently a very healthy nearly 2 year old - although during the pregnancy, we weren't sure if she'd survive.
When it's all said and done, while most miscarriages do happen in the first 13 weeks, there are always risks and after my experiences, I think I'd still want to tell everyone early rather than later. That way, they can be with you for the journey and all the ups and downs that are on the way. Just my experience
