I tell my parents after my first dr. visit. I tell my inlaws around the 3rd month, sometimes later if i’m carrying smaller. (In laws cant keep their mouths shut…) Siblings, similar to parents and inlaws due to the same issue.
I dont feel that you have to tell friends. They’ll find out when they find out and thats it. I may hint to it when i’m talking to them, for example “I’m moving into my parents for pesach because it’ll be easier for my situation”. Something along those lines, but i dont tell them outright.