Re: Timeline of Nolan's trilogy.
I believe that when Nolan made TDK he did not have TDKR in mind so at the time TDK probably takes place a year or two after BB. But since he went ahead and put an 8 year gap between TDK and TDKR I think in his head and in theory as a service to the character he gave Batman a longer career and a bigger gap between BB and TDK (4-5 years or so)
There is a ton of evidence to support the idea that TDK takes place 4-5 years after BB (Gordon's kids, no mention of the Narrows, etc) When asked "why 8 years?" Goyer said something to the effect of "We wanted enough time to pass so that Batman's legend could be starting to fade. If he was only Batman for 8-12 month I don't know how much a legend he would be. Batman 4-5 years yes that's legendary IMO.
But at end of the day each movie is made to stand on its own and only geeks like us need to dissect things like the chronology and so forth.