After you've bought it in the store, you get an email telling you they will email you the ingame code to claim the pet in 5 days time (this was UK, I'm sure it's the same for every other region).Sorry I didn't realise this info had already been posted on pages 2 and 3, I only checked the first page and I can't work out how to delete this comment (what a noob).
Just ordered mine (in the UK) the code for the in game pet will take upto 5 days before its received.cant wait I love Murlocs and this pet will be my new Dracthyr Ice mage companion on their, adventures together
On the UK store we have this information at the bottom of the page :"Limited time offer, while supplies last. 252 codes available to be redeemed."Happy hunger game !