When did you or are going to tell work?

I am 13 weeks and 1 day. I had an ultrasound at 11 weeks and everything looked good. I won’t have another until 20weeks with my doctor but we will probably go to a private clinic for a 3D ultrasound before then. I haven’t told work yet because I’m so nervous. There’s been a lot of changes and I’m nervous about adding more. When did you tell work or plan on it? Should I wait for another doctors apt to confirm everything is still ok or just go ahead and let them know so they have a long notice?