There's a good reason why people are calling for a relic heirloom. As far as I can recall, from leveling my pala a few months ago, the first relic you can get is at level 40. From Scholomance. More annoyingly it's a sta/int/spri relic, so nearly useless for anything but holy palas. The only advantage it has is the ability to take any WotLK epic gem.
Past that the first actual tanking relic is Relic of the Paragon from a quest involving Stratholme; a quest that can't be done before level 46.
Even if the heirloom had no XP bonus it'd still be VERY useful as getting relics before about level 60 isn't straightforward.