The February Holland Herald has a page about the WBC retrofit
The last of the 22 Boeing 747s is scheduled to be delivered with a new interior in May 2014.When these are ready, KLM E&M's team will begin work on 15 Boeing 777-200s in the fleet, which are to be done by the end of 2015. The Boeing 777-300 and Airbus 330 aircraft will then follow.
I hope the 2015 is a typo!