I got a code sent to me the last time he went on tour, saying I was in the top 10% of listeners. It didn't come until like 6 hours after the tickets went on sale though, which at that point was totally useless.
Pre-sale codes are sent to people who listen to an artist a lot according to Spotify's streaming data. If you haven't received a pre-sale code, I'm afraid you are not eligible for this one. You can read more about pre-sale codes on this page! Let me know if there's anything else!