Federal judges have begun to fast track certain types of cases over the past few years for purposes of judicial economy. I would think that if the case has to run its entire course in formal litigation, rather than being resolved through settlement (which I believe far more likely), it may take a couple years, but I wouldn't think any more than that. I believe the outcome of the OSC proceeding is going to have a great impact on the outcome of the civil class action lawsuit in terms of its "settlement value" and the speed in which it may be resolved.
I need to check PACER and contact the attorneys for the current status. I'll report back.