I don't think this is a stupid question. Deciding when to tell others you are pregnant is a very difficult decision. If you tell others early, it may factor into their decisions on what to include you in. If you tell others late, they may be frustrated that they weren't told earlier, and again factor that into their decisions on what to include you in. People have different expectations on when is the right time to know, and react in very different ways. It is a dilemma with no clear answer because of how varied people's expectations and reactions are.