This took place as a first registration while Quirinius was governing Syria.
(And this taxing was first made when Cyrenius was governor of Syria.)
This was the first enrollment, and it was made when Quirinius was governor of Syria.
This was the first enrolment made when Quirinius was governor of Syria.
This first enrollment occurred when Quirinius governed Syria.
This was the first enrollment; it was made by the ruler of Syria, Quirinius.
This enrolling was first made by Cyrinus, the governor of Syria.