Questions about eight characters ...

9 o'clock is the demarcation time between Chen and the company, so it must be clear whether it is before or after 9 o'clock.

If it is before 9 o'clock, when Chen Bing is on the fifth day of the fifth lunar month in Gui You, the eight characters are "Chen Bing on the fifth day of Gui You"

If it is after 9 o'clock, on the fifth day of the fifth lunar month in Gui You, these eight words are "the fifth day of Gui You"