Jhin's E is useless ATM.
So lately, Jhin players (myself included) have been taking E at level 13, and even then, it seldom is used during games. I would say the only time I'd take it earlier than level 13 is if there was an Eve or Shaco on the opposing team. The skill definitely isn't "useless", but it doesn't do much for Jhin's kit. You get more than enough CC with the root from the W. No one ever gets hit by the explosion of the E, it's only there to proc the W.. discuss? Maybe have it pop a little quicker?