During the Attack on Titan 2 livestream, Koei Tecmo has confirmed that the game is planned to launch in March 2018.
Previously Koei Tecmo confirmed that they are planning a simultaneous launch for Attack on Titan 2 worldwide. That said we can expect the game to arrive in the west in March 2018.
A few more details have been revealed for the game, such as character customization and the inclusion of two new characters, Chris and Yumiru. Screenshots can be found below.