@mazman1381
I do see that you have already received some replies but wanted to share the IRS link: https://www.irs.gov/faqs/interest-dividends-other-types-of-income/gifts-inheritances/gifts-inheritan...
I would agree that it would be easier to file a gift tax return for the whole amount upfront. Than to have it be done over several years. There may be advantages for homestead exemptions etc. to have the deed only in your sons name but that is a separate consideration.
Also if there is mortgage the bank may have stipulations on how the gift is documented. So there are several considerations on that topic as well please see this article: https://www.chase.com/personal/mortgage/education/financing-a-home/gift-money-for-down-payment
