My German is very dodgy and I haven't used it in six years but it is just good enough to understand your post There will be a beta but it won't be a conventional "early access" build (they intend to have little or no story content in it). As for your actual question the devs haven't said anything about when it'll be available but the game is set for a release sometime in December this year so... sometime between now and then.
Unfortunately my english is pretty bad! Aber danke für die Antwort After all, one who understands me :D würde mich freuen wenn jemand auf deutsch Antworten würde!