Just read the facebook link. Yes, it says the rollover miles from the 2011 balance will be taken into account mid-2012. So they start with the benefit earlier than I expected because I thought they would not introduce the benefit retrospectively. Maybe people were so annoyed about the credit card change that they felt they had to speed it up. (At least I have no other explanation for this. Normally you would expect an airline to introduce a benefit only when it serves as an incentive for future behaviour.)