I booked a 2-bedroom flat in May 2014 and initially we were told that it will be delivered in March 2017, then they changed to 2018 and now they are telling that end of 2021.
On the other hand, they are still taking all the payments. So I will say avoid this builder or buy a ready to occupy flats only.
These builders are bad and will suck your money. Mantri seems like known to delay projects. They delayed Mantri serenity also by 4 years.