So i bought and Redeemed the steed...

http://forums.worldofwarcraft.com/thread.html?topicId=24261280628&sid=1&pageNo=1#3

Q u o t e:
Pet/Mount Not in Mailbox

If you have purchased the Celestial Steed Mount or one of the various pets from the Pet Store and it has not yet appeared in the mail, please exit the game completely and log back in normally. In most cases, this will refresh the necessary character information and the in-game mail containing your new pet/mount will be sent. Please be aware that processing and delivery may take in upwards of 1 hour.

If you just recently made your purchase and completed the redemption process, but have not yet received the Celestial Steed, go ahead and complete the steps noted (exiting and reloading the game client). If you do not receive your mount in the mail within the next hour, please let me know and I'll look into the matter further.