when to announce pregnancy

I'm almost 15 weeks pregnant and still haven't announced my pregnancy to the majority of my family or my place of employment (The only people that know I'm pregnant are my boyfriend and my mom).  I'd like to wait til absolutely necessary or until I can't hide the bump anymore. Originally it was because I am high risk of having a miscarriage but now I guess I'm just stalling because I'm unsure about how everyone will react :/ Is that weird? When did everyone announce their pregnancy to their boss/work? Is it rude to announce it late like I am?