Drop Proctor Aviation an email and ask, they've just started sending out unsolicited emails for A320 so the game's on.
Could be other agents but certainly Proctor.
Main thing for Vistara is they're supposed to have made a decision by end of June - today! - whether to go Neo's or roll over to Max's, muddied the water by ordering 8x787's and no one's willing to take bets who wins narrow body....but the interest by local pilots in the final decision is very high.
Cheers.