I have booked a flat on 17.2.2019 and paid Rs.90000 towards booking advance. On the day of booking, builder took a post dated (5.3.3019) cheque for an amount of Rs.3,00,000 . After a week from 5.3.2019 I have to pay another installment of 11,00,000 and sign the agreement. There will be another installment of Rs.3,00,000 to be paid before March end. As per the cost sheet given by the builder at the time of booking, 12% GST is charged for each instalment payment. In order to take advantage of reduced GST rate of 5% from 1.4.2019 onwards, I am contemplating to postpone all my payments due in March to 1.4.2019 by issuing a post dated cheque to the builder for the total amount due in March. I have requested the builder with my above proposal but he is yet to respond. Do I have the right to defer my payments to get GST advantage since I have not signed any agreement so far.?