Just wanted to know when exactly the events of the dark knight took place??
We can assume only a year after Batman Begins because the Joker was robbing banks at the end of Batman Begins.
Probably took place even before that, like 8 months after Batman Begins.
Which means, Batman was only around for a year.
Then he disappeared for 8 more years until saving Gotham from Bane.
So his legend as Gotham's superhero was very brief.