To some degree the language does not matter. What matters is that the kid is ready for the abstract thinking required for programming and that he or she wants to program. My son, then 10, spent a week programming w/ Scratch. He enjoyed it but then abandoned it because there was no relationship between his life and what he could do within Scratch. If Scratch connected to the outside world (think Maker and Instructables here) he would have continued further (I think). Kids think of programming like drawing a specific picture or building a play structure. I do it now and I am done. For them, it is not an intellectual journey.
