Re: Timeline of Nolan's trilogy.
“The Dark Knight” took place in the summer of 2008. The security camera showing the Joker have a timestamp saying they were taken on July 17, 2008 and the court documents in the RICO conspiracy case confirm that this trial is also held in July 2008. I would say that the events of “The Dark Knight” likely stretch at least into August.
Now, when the Joker is talking to the mob (I propose we kill the Batman), he instructs them to recall a year ago, before Batman, which sets a maximum time-elapsed between the two films of approximately one year. Most people estimate 6-9 months, which would be consistent with the fact that Bruce’s birthday is in February and his birthday party is seen in “Batman Begins.” This means Batman Begins either took place in the second half of 2007 or early 2008.