Are you working in a stock market or have you ever traded in the stock market? If yes, then it is obvious that the initial price of the stock would be much less to attract the buyers. This low price is not because of the low performance of the company, it is to gain the loyalty of the buyers. Once the buyers are confident and the market value of the company has increased, the stock value would also increase. With very minimal constraints that impact the price, the stock value would be stable. The same analysis would be applicable to the house that you want to buy from a builder.
There are chances that the builder though has reputation and have spread their fame by doing multiple projects it is obvious that they still offer a reduced price on the new residential or commercial projects that they start. So, just have a look at the previous situations and understand what sort of variation in price has been enjoyed by the buyers who have booked their house as soon as the project is launched. If you look at these facts you would no wonder would quickly book a house for self from the ki residences new launch.
Also, the booking would not demand you to make the whole payment, only a partial amount would be required and a gap of an year or whatever is the practice of the developer would be applicable on any project they do. So, this gap between transacting for the booking of a house and to make the part payments could be utilized by you to source the amount and thus reduce the unwanted interests that you have to pay for the banks for taking the home loans. Hope this make more sense as to why you should buy the house when the project is launched by the developer.