If I recall rightly you meet him very soon after you cross the bridge.In farm area,He talks about problems with trolls[Gives location of Troll cave] and also about another farmer who saw his child torn apart by trolls. He's standing outside his home.Sorry can't remember more.
I think this may be an easy quest to break. I never received the quest. Although I had spoken to Homer, I did not get the speech options from him necessary to initiate the quest. I am not sure what I did or did not do to break it.