Tsewang Rigzin is the current president of the Tibetan Youth Congress. He has held the position since September 2007, and on August 8, 2008 he was re-elected to serve through August 2013. Prior to attaining his current position he served as the president of the Portland/Vancouver regional chapter of the Tibetan Youth Congress.
Rigzin worked for the Tibetan Youth Congress prior to 2007.
The context states that Rigzin was president of a chapter of the Congress prior to 2007, when he was elected to the presidency of the full organization. Thus, he has worked for the organization in some capacity since before his election in September of 2007.