At what point do you tell your buddies you've been talking to/dating someone new?

I'm wondering because the guy I've been seeing asked me if anyone knew about him (my best friends do) on our first date, which was after we had been talking for a month. I asked him the same question and he said that he had told his buddies he was talking to me. So I'm curious, when do guys tell their buddies about new relationships? Is that a good sign?