The release date at SDCC was January 2013, but someone in America has apparently found some Kreo Microchangers (blind pack ones) at a comic shop.
So what does this mean?
Maybe the January date was for a general retail release and these are just a small "preview" wave... or maybe a small batch were released to a select area/stores, like a test market, to make adjustments before their big release in 5 months time.

Either way, the news posting link above shows us what the packets look like, and more importantly, that they were stamped with numbers that match the product numbers on the instructions/checklist sheet inside, to make it easier for us fans to know what we are looking for.
(something I hope they keep doing)