Q: When could you listen/look at someone say this person has potential to start making music?
A: that's kind of a catch 22. anything that is really a sure sign that someone has music in them, could most likely be considered music which means they've already started making music. For example, if someone takes a few steps with their shoes on the ground in a sort of musical way, .... and you may be thinking 'hm, that person should start making music'. well, it's too late they already started