I haven't played much during the later part of Cataclysm so my gear isn't that great, In the beta it doesn't matter much since all gear is normalized when in dungeon(All gear is set to ilevel 390 no matter previous ilevel), but once it goes live I am afraid my gear will be lacking to tank instance so my plan was to DPS and grab tank spec rewards until I have enough gear to tank my self.
But in MoP Blizzard introduced 'Dynamic Quest Rewards' making the quest only offer you rewards useful for your class/spec. So my question is when is reward decided for a Dynamic Quest Reward? Do I need to be in tank spec when picking up the quest, when handing it in or both?