What would Jesus Christ's date of birth be written down as, either in numbers or Roman numerals?

The actual date and time of Jesus birth is not known.
However, if you are referring to the date defined by the Roman authorities in 525AD (which was 1277 AUC using the Roman system) Jesus was born on 25 December 1 BC
The year would have been recorded as 753 AUC, or in Roman numerals, DCCLIII

In the 247th year during the Diocletian Era (based on Diocletian's ascension to the Roman throne), Dionysius Exiguus attempted to pinpoint the number of years since Jesus' birth, arriving at a figure of 753 years after the founding of Rome. Dionysius then set Jesus' birth as being December 25 1 ACN (for "Ante Christum Natum," or "before Christ (was) born"), and assigned to the following year "AD 1", "Anno Domini 1", which translates as "in the year of Lord", thereby establishing the system of numbering years from the birth of Jesus. The system was created in the then current year 532, and almost two centuries later it won acceptance and became the established calendar in Western civilization.

https://en.wikipedia.org/wiki/Jesus

Of course, there is evidence to suggest that Jesus was born at the beginning of spring, around Passover. In such a case, local documentation would have the date as "15th of the month of Nissan, in the 4th(?) year of Herod's reign."