If you are thinking of buying a brand new home from a tract home builder expect lotteries to get on a waiting list. There is little if any standing inventory in many markets. And, many builders may not commit to a final price because the cost of building materials is going through the roof. Further, if you are lucky enough to land a home, expect it to take 10 - 12 months to complete from the time you sign a purchase contract. Many people are selling their current homes quickly because the markets are so hot and then finding themselves with no place to live.
If you do sell your home and must wait for the new home to be completed, you may need to rent a home or apartment and put things in storage. Rents are not cheap and neither is storage. Try to do a six month lease if the owner will agree and then month to month after that with 30 days notice so you can move quickly when your home is ready. Don't be surprised if the landlord demands a 12 month lease. Though you will pay more, if you rent big storage lockers, make sure they are temperature controlled because otherwise, your furniture and other belongs could be ruined from excess heat during hot months.
If you do buy a brand new home, expect to pay at least 20 - 30% above the list price for upgrades and lot premiums. What you see in the models are highly upgraded homes. What you get without the upgrades is really crap. This can be a very frustrating process; but with a little patience, it can be done. If you are thinking of building a custom home expect a 2 - 3 year process from start to finish and a whole lot more money.