I have purchased two new homes in new housing developements. In the 1982 I purchase my first home in Montgomery county, PA. We were the 20th home built in a development of about 200 homes that took two years to complete. By the end of construction our same model was selling for 15,000 more than what we had contracted. I might add that interest rates were 19% and our builder had a buydown wiith a lender and we got our first mortagage for 13% and were delighted. In 1987 we purchased a new home in a development in Langhorne, PA. We were the 15 house built in a developement of over 200 homes and by the time we went to settlement 6 months later our model was $ 48,000 higher. We could not have bought in that area if we had waited as it would have been price prohibited. We would later sell this house three years later for double what we had paid. I will say that builders will typically hold back premium lots in the later stages ( as a means to achieve higher prices on the same models later in the project. So based on my experience , it sometimes pays to buy earlier than later.
I will point out that we are in different times, you must have confidence in the builder, does he have the financial stability to operate in this current housing downturn and finish the 100 home tract? Is this a large national, regional or local builder? It can make a difference. If I were to do it over in this market, I would probably wait until at least 50% of the project is completed. A good local Realtor should provide you with the guidance to ask the necessary questions. Good luck. This is a great time to buy a home.