With my first 3 pregnancies close family were told pretty much straight away. They all ended in early m/c's (age related, so don't let that worry you). I wished they didn't know as although they meant the best people often said the wrong thing which made things worse. On the other hand it was good to have people who knew what we'd been through. I only told work friends after the fact.

When I got pregnant last time we told close family I think at about 8 weeks (was past my personal danger period by then) and friends and work colleagues at 12 weeks.

As it was some people had already suspected. My SIL had noticed I wasn't drinking at all and didn't really believe my excuses (she was pregnant herself so had just been through hiding the fact herself). One work friend suspected my absences from work could be due to a pregnancy and my closest work colleague actually thought I might be going for IVF and that's why I had a couple of absences and that it would explain why I kept bursting into tears at my desk.

Go with whatever is comfy for you. I truly don't know which way I'd go if we had another one but I'm guessing we'd probably tell before 12 weeks as it's just so hard to hide the fact. I was extremely lucky that I didn't have MS. If you do get it, it can be almost impossible to hide the fact from others.