I voted "specify." I suppose I would be closest to "they hit me first" but it wouldn't get to that point. In that situation, you never let them strike first becasue you don't know how good they are at fighting, whether they have a weapon, etc. If you let someone throw the first punch and they are a professional MMA fighter, then obviously they're gonna be able to put you down in one or two hits.
I also dislike the idea that fighting is a way to "settle differences" 50's style. If a situation comes to blows, I'm going to hurt you. End of story. One or both of us will not be walking away of our own accord if it gets to that point. Fighting is a last resort. So if I can end the fight without risking harm to myself or others, I will, even if they haven't thrown a blow yet.
I also dislike the idea that fighting is a way to "settle differences" 50's style. If a situation comes to blows, I'm going to hurt you. End of story. One or both of us will not be walking away of our own accord if it gets to that point. Fighting is a last resort. So if I can end the fight without risking harm to myself or others, I will, even if they haven't thrown a blow yet.