I've used the credit for both 2012 and 2013. 2012 for a CX flight and 2013 for an AC flight.
Looked on the CX/AC website and called PTS to ask specifically for the flights I wanted. Price quoted by PTS was exactly the same as the website. After booking, asked that the credit be applied and it was done! Saw the booking and credit on my online statement a few days later.