This was the eighth of the priestly courses of ministration in the Temple (I Chron. 24:10), and occurred, as did the others, twice in the year.

The "Courses" were changed every week, beginning each with a Sabbath.  The reckoning commenced on the 22nd day of Tisri or Ethanim (Ap. 51. 5). This was the eighth and last day of the Feast of Tabernacles = the "Great Day of the Feast" (John 7:37), and was a Sabbath (Lev. 23:39)

The first course fell by lot to Jehoiarib, and the eighth to Abia or Abijah (1Chron. 24:10).

Bearing in mind that all the courses served together at the three Great Feasts, the dates for the two yearly "ministrations" of Abiah will be seen to fall as follows:

     The first (*1) ministration was from 12 - 18 Chisleu = December 6 - 12.
     The second ministration was from 12 -18 Sivan = June 13 - 19.

The announcement therefore to Zacharias in the Temple as to the conception of John the Baptist took place between 12 - 18 SIVAN (June 13 -19), in the year 5 B.C.  After finishing his "ministration", the aged priest "departed to his own house" (Luke 1:23) which was in a city (*2) in "the hill country" of Juda (verse 39).

The day following the end of the "Course of Abia" being a Sabbath (Sivan 19), he would not be able to leave Jerusalem before the 20th.

The thirty miles journey would probably occupy, for an old man, a couple of days at least.  He would therefore arrive at his house on the 21st or 22nd.  This leaves ample time for the miraculous "conception" of Elizabeth to take place on or about the 23rd of Sivan (*3) - which would correspond to June 23 -24 of that year.  The fact of the conception and it's date would necessarily be known at the time and afterwards, and hence the 23rd of SIVAN would henceforth be associated with the conception of John the Baptist as the 1st of TEBETH would be with that of our Lord.

But the same influences that speedily obscured and presently obliterated the real dates of our Lord's "Begetting" and Birth, were also at work with regard to those of the Forerunner, and with the same results.  As soon as the true Birth day of Christ had been shifted from its proper date, viz. the 15th of Tisri (September 29), and a Festival Day from the Pagan Calendars substituted for it (viz. December 25), then everything else had to be altered too.

Hence "Lady Day" in association with March 25 (new style) became necessarily connected with the Annunciation.  And June 24 made its appearance as it still is in our Calendar, as the date of  "the Nativity of John the Baptist", instead of , as it really is, the date of his miraculous conception.

The Four "Quarter Days" may therefore be set forth thus: first in the chronological order of the events with which they are associated, viz.:
 

or, placing the two sets together naturally : --
 

(*1)  Reckoning of course from Ethanim or Tisri - the First month of the civil year.  The sacred year was six months later, and began on 1st Nisan.
(*2)  The "city" is not named (possibly Juttah, some 30 miles to the south of Jerusalem).
(*3)   The conception of John the Baptist was, in view of Luke 1:7, as miraculous as that of Isaac; but it is not necessary to insist upon the complete period of forty sevens (p.198) in the case of Elizabeth.  Therefore the birth of the Forerunner may have been three or four days short of the full two hundred and eighty days, - as indicated in the above table.