When are you telling your manager and co-workers?

Annabela
We haven't told anyone we are pregnant. We are planning on telling our families at thanksgiving and then announcing with our Christmas card. 
When are you telling your manager or co-workers? I have 2 doc appts which I had to schedule during work hours. I let my manager know the dates and times of the appts but didn't say what the doc was for. I usually tell him everything and he is extremely supportive of everything. Suggestions?