The more I think about it its unlikely Bruce retired immediately after TDK. Maybe 6 months to a year at most. He did rebuild the Batcave. Also for the public to buy into the deception G0rdon and Batman created they would have had to play it out for some time. With the police trying to relentlessly capture the fugitive. With Batman perhaps almost in a Green Hornet role. Appearing to be a crminal to end his "competition".