The Arhkam City Story 'Open For Business' states that it's been 18 months since the events at Arkham Asylum. A plaque outisde Wonder Tower in Arkham City stated that the prison opened on November 19th, therefore puts AA in May of the year prior.
The game has put The Joker's breakout on 23rd December, and The Road Of Arkham states Batman was finding Joker for 2 months; after knowing that AA is May, this is a complication (a lot of the comic has conflictions with the game). I decided that it was two months since Joker escaped arrest in 'A Matter Of Family' DLC (If this doesn't work, then the comic is a large contradiction).
I've heard a lot people talking about this but I've seen any evidence myself, if you can provide that then it requires a change.
The comic claims that he fought Zsasz, Scarecrow and Joker within a month.