Megansmama wrote an excellent thread with tips on reuniting lost dogs with their owners.
http://www.yorkietalk.com/forums/yor...ir-owners.html I think the most important tip is the think "lost not stray." I guess you should do what you would want others to do, if they found your dog. I think you can "foster him" for several months, while looking for his home, and don't forget to notify animal shelters if you haven't done that already. I think after 6 months, I would consider it mine, and stop looking. I think a minimum of 3 months is needed.