3. Excuse me?
Back in the day when I first began to do fieldwork, I met someone who just got his Ph.D. (and truly felt like he was it). While we were out there, an old friend who he hadn’t seen in years came up to him and greeted him using his first name.
He actually stopped the person in the middle of their sentence and said “Excuse me, my name is Dr…___” and he was absolutely serious. This was about ten years ago and I now have a PhD but I wouldn’t imagine doing that to anyone.
Really, the only people who refer to me as Dr are my students (if they don’t use professor) or if I am at a conference or something and that is absolutely fine by me.