Re: How Long Was Bruce Wayne Actually Batman in this Trilogy?
I don't know how long the events of Begins go on, but between Begins and Dark Knight 6 months pass. Between Dark Knight and TDKR, 8 years pass, but it's mentioned that Wayne has only been reclusive for 3. The last "reported" sighting of Batman was 8 years prior, but I don't think they ever specify that sighting was Dark Knight's finale.
At any rate, considering how Batman operates in the shadows, it's perfectly legitimate to say that he had only been retired for three years as of TDKR. There just weren't any city-destroying master villains in between that time.
So I'll throw out 6 years or so.