Both Frank Miller's seminal Man Without Fear comic miniseries and the Netflix TV show adaptation touches on the critical training Matt received from Stick.
Though they both skim over the how-they-even-met part.
So is there a clear explanation or a flashback in the canon that reveals how Stick knew just when and where to find Matt?
Was there was some Chaste derived "Chosen One" type of prophecy that mystically led Stick to Matt? Or did young learning-to-use-his-gifts Matt do some amazing news-worthy feat that attracted the Chaste or Stick's attention?
UPDATE:
Added a few images to help connect the dots between the comics canon and the show as it relates to this question. This convinces me that something was known to the Chaste well before, though I just don't know how and when this happened.