Depends on when you'll get the delivery. If the current own rates from dealers are 50k, that means with the 20k commission of the dealer, you'll only get 30k and that's right now. Who knows how bad the situation for investors will be in a month or two.
One of the major reasons why own rates are down in the market is because before the 1 lakh extra for registration could be avoided if getting it registered after 3 months. Now there's no limit and even if you get registration after a year, you'd have to pay 1 lakh extra if you bought on own. Combined with city being overpriced (especially 1.2s), overbooked, loads of them available in the market, and the Yaris 1.3 being much cheaper and almost readily available or readily available with very low own, city 1.2s are for sure gonna be selling under invoice soon. If I had a 1.2 booked and it's delivery was any later than October, I'd just eat the 20k cancellation charge or upgrade to 1.5 or aspire and wait a bit more.
I'd suggest to buy new, choose between 1.5 Yaris or 1.5 base city, there's good comparisons of those 2 on this thread. If you wanna save some money then 1.3 Yaris is a good option. Don't go for 1.2 city in any case.
