Every transaction is unique. Each home builder has different protocols which are also based upon the specific subdivision. Most importantly, negotiating a discount on an inventory home usually comes down to the builders motivations: end of month, quarter or year quotas they are trying to meet. Best of Luck!
I suggest your Realtor do the research & work with them. Best of luck.
You hired a Realtor to help you with your home purchase, so it's only proper for you to get your advice from your Realtor.
Tierra Antigua Realty
The house may have been built 10-20-30 years ago, and the cost to build it would be nonesense in today's market.
No so with a new-construction: The Builder knows what it cost them to build it, and they know what margin they need to make.
You can bet that the LIST PRICE is padded a little, maybe more than a little.
But you can also bet that they will not agree to a Low-Ball offer; they can sit on it while it appreciates.
The bottom line is; What is the house worth to you? How much do you love it? How closely does it meet your needs?
Try not to be emotional about it.
Good luck and may God bless