Historian Llore in Stormwind and Historian Ju'pa in Orgrimmar are the questgivers for the anniversary event.
They also sell Corgi Pup for 200 Timewarped Badges!
Yay! More dogs to keep the scheming cats in check!
Edit: great point from Ignis on EU forums http://eu.battle.net/forums/en/wow/topic/17614451666
Rather than using the 200 Time-warped badges from your "main" simply create a new level 1 character or log onto an alt to receive another 200 badges through your mail, then purchase the corgi on that character. BattlePets are Account-wide after all.
I saw many players complain about having to spend their badges on the pup so I thought why not put this info out there for people who are not aware of this.