From the Rio-Tinto website, concerning the new copper stream.
In December 2012, the project took a major step closer to commercial production with the commissioning of the concentrator. Alongside senior management from Oyu Tolgoi, Mongolian Mining Minister D. Gankhuyag pressed the button activating the concentrator for the first time, at a ceremony also attended by members of parliament, members of the cabinet and ambassadors. Completed in record time, the concentrator is Mongolia's largest and most technologically-advanced machine.
With the concentrator online, Oyu Tolgoi will begin producing copper concentrate in the first quarter of 2013. Commercial production is expected within the first half of 2013.
Now the big question. Is this being produced from the Heruga and/or Hugo North Extensions. Either way it looks like copper production is beginning.