I've come out to maybe 100 people myself. Typically one-on-one, occasionally in a small group. I prefer the single interaction because they ask questions. No one asks questions in a group setting.
Yesterday I tried an experiment. There wss someone I needed to tell and I ran into him as we got on an empty elevator on the seventh floor. I told him everything before we got to the lobby. It was actually funny. We chatted for a minute in the lobby. His only question was interesting, "Is congratulations the right thing to say?" My response, "yeah I guess.... Mostly."