@urchinstar47 It's planned for whenever they release it. See the first post in this topic ;-) And you probably won't get an official answer that says any more than that.
However, I think what I remember from the release announcement is that they're hoping to release them when the main story gets translated to the point when the book was released in Japan. Except that the first one was way late due to when they got the license and was released at almost the time the second one would have matched up with the main story. So I'm betting the second one is getting an intentional delay just to avoid having them back-to-back. My guess (mind you this is just a guess, I have no inside info) is if you figure out which volumes in the main story the 2nd and 3rd fanbooks match up with, the 3rd will probably release at that time, and the second will probably release halfway in between when the 2nd and 3rd should have (since the 1st released about a volume prior to when the 2nd should have)