You can't guess someones type until they are in their late teens. MBTI is not made for children.
^ i think on the personalitypage.com site it described that the NF or SF etc. part of your personality is formed first, and the I/E and J/P distinction comes later. so in that case, he could already be at least an "NF".
advice for raising an NF kid: engage his imagination and value his feelings C: