But what about here? What have you always heard Lacroix say? Janette calls the musicians "common street players," but if they are Nick's students, she is being facetious in that remark, teasing him -- and it changes the complexion of her murder of the girl. Perhaps the three of them came on purpose to hear the boy and girl perform, from Nick's perspective (though he didn't successfully communicate that to Janette). Regardless, if indeed the word is "your," then we know Nick's occupation at that time! And what a Nick-like occupation, combining teaching and music, both of which he loves.
(And how often we make him a music teacher in fanfiction! Dorothy's "The Gift" leaps to mind, and even I did it once in flashbacks an age ago.)