BikePedia isn't the be-all and end-all, but they show the OCR C1 being made for the 2007 and 2008 model years. Does yours match the paint scheme and components on either of these?:

2007 Giant OCR C1
2008 Giant OCR C1

Another way to date the bike: If it has Shimano components and they're original to the frame, you can check them for date codes.