The much anticipated Attack on Titan season 2 was originally scheduled for July of 2015. Several sources are now confirming a 2016 release date.
Apparently WiT Studios wanted the manga to get ahead of the series. I wouldn’t expect an early 2016 release date with the mange trailing the original Attack on Titan debut season.
Possibly another factor of putting off season 2 is the upcoming live action movie release compilation of season one, Attack on Titan Part 1: Crimson Bow and Arrow. Attack on Titan direction, Tetsuro Araki, announced that scenes from Attack on Titan season 2, will appear in Cromson Bow and Arrow. A second movie, Attack on Titan: End of the World is also scheduled to release sometime in September. Comson Bow and Arrow is reported to cover the first 13 of 34 episodes of season 1 and End of the World will cover the remaining episodes of the initial season.