You will not incur any gift tax liability until you reach the 2023 lifetime exemption of $12.92 million.
If your individual gift is valued at more than $17,000 to one other person (e.g., your son), then you will have to file a gift tax return (Form 709), but there will be no tax due until you surpass the limit noted above.
See https://www.irs.gov/pub/irs-pdf/f709.pdf
