The specific birth marker is the night that is no night. However, other omens in the heavens and on earth had been prophesied, also signs to prepare the world for the Messiah’s coming. When “angels did appear unto… wise men,” these individuals were almost certainly believers who correctly understood the signs. Unbelievers continued to ignore the signs and reject the gospel.
Chronology: The ninetieth year of the reign of the judges is approximately 6 B.C., about two years prior to the Messiah’s birth.