When is reward decided with Dynamic Quest Rewards?

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?

Solution 1:

The quest reward changes with your spec, so you just have to be the spec needed for the desired item when handing in the quest.

To show this I made this video:

This is also true for Dungeon quests that award rare items(blue)