Generally speaking, on February 9, 20 10/kloc-0, you don't write the Gregorian calendar, but you are writing such an autograph.
Write the sixth day of the first month of Gengyin year or the early spring of Gengyin year (author's name) on the lunar calendar, and so on. You can also write the spring month (place name or another name of your specific Zhai Guan) in the year of Geng Yin (author's name) in * *.
It depends on the content. Generally, hard-pen calligraphy doesn't leave long paragraphs because of the content, does it?
You can learn more about the traditional lunar calendar, which is very helpful for calligraphy.
See if it helps. I'll contact you later.