The word on the street is that it might take place in mid-February but that is also dependent on when chancellor Olaf Scholz will be expected to face a vote of confidence. As things stand, the latter is scheduled for 15 January next year. If that is brought forward, then there is a good chance of the election taking place sooner. If the original schedule is upheld, the election should take place in late March instead.
Update: Focus Online says that the confidence vote could be held on 18 December while Rheinische Post reports othat the proposed date for the election is on 23 February currently.