Personally I would get him started on Guitar....if you started hom now he could be amazing by the time hes 14...when hes an adult he might be a famous guitarrist...but I play some Piano, and trumpet too, and it is good to learn the basic note structure though they are fundamentaly different. So...you choose do you want a Mozart or Jimi Hendrix? Guitar Players make more money, I am pretty sure. And yes they make small kids beginner guitars