Ok, so when he & Kakashi first started their mission with Kakashi, he was considered to be a Chunin.
Now this is where it gets funny, because I personally think that the second he unlocks sharingan he acutually surpases Kakashi (which may be untrue, I agree) but it's definately enough in my mind to push him up to Jounin (considering Kakashi was made one)
Now, when he unlocks his MS, what would you consider him? :D
*lemme give you a hint, he's raping ANBU & Jounin