So just to be clear - the year of Herod’s death - would be 6 A.D. He began his rule in 4 B.C.
No, Herod the Great—the one usually meant by “King Herod”—died in 4 B.C. We have other sources for him besides the New Testament. Matthew calls his son Archelaus, not Herod Archelaus. Archelaus did not die in A.D. 6 but was sent off to Gaul.