Hey Lulabell,
I told work last week, only my manager but that's cos of where I work, (in a prison) and I could be put at risk if I carry on going on the wings. I think it depends work kind of work you do on how soon you would need to/want to tell work. If I had my way I would have waited till I had the 12 week scan, but OH would't have it!
Hope that helps!
x