Usually, in the games I played, I build a worker as soon as possible. Even with that, I'm ending up in a good position. So, is it bad? I'm not very sure... cause, yes, it will slow your city's growth at the beggining. But then, you can improve some tiles with it. so, in the long run, it ends up, I think, to the same as if we decided to build a warrior first. No?