You can choose Gregorian calendar or lunar calendar. The Gregorian calendar is pragmatic, while the Lunar calendar is pragmatic.
Gregorian calendar: 20 1 1 May/0/5th.
Inscription of the Lunar New Year: Xinmao Year, in the middle of Huai month (20 1 1 year is Xinmao Year, and May Day of 15 is the 13th lunar month; The fourth month of the lunar calendar can be called lack of moon, locust month, mid-month, wheat month, clear and harmonious month, cloudy month, full moon, locust summer, early summer, early summer, Xia Wei, Zhengyang, Chunyang, Maihou, Xia Meng, Lv Zhong, Mitsuki and so on. The dates recorded in the old calendar are divided into the upper, middle and lower rings, with the first to the tenth day as the upper ring, the eleventh to the twentieth day as the central ring, and the 21st to the thirtieth day as the lower ring), which can also be directly recorded as "Xin Mao's New Year's Early Summer".
Gregorian inscriptions can clearly record the creation date of a work, so many contemporary calligraphers push this move.
Of course, learning ancient calligraphy can get its charm, and the lunar calendar is still the first choice for many calligraphers.