User blog comment:Der Schreiber/Announcement for the ME3 demo this Wednesday!/@comment-2228081-20120123222343/@comment-3268946-20120123235925

Basically the demo is released on the 14th and if you have early access the multiplayer portion is immediately available to you. If not, you have to wait until the 17th. But hey, at least those without access will still have the singleplayer portion.