6 And they were both righteous before God, walking in all the commandments and ordinances of the Lord blameless.
7 And they had no child, because that Elisabeth was barren, and they both were now well stricken in years.
8 And it came to pass, that while he executed the priest's office before God in the order of his course,
9 According to the custom of the priest's office, his lot was to burn incense when he went into the temple of the Lord.
10 And the whole multitude of the people were praying without at the time of incense.
11 And there appeared unto him an angel of the Lord standing on the right side of the altar of incense.
The altar of incense was made of acacia wood with a veneer of gold. Acacia is a beautiful hardwood that is almost indestructible by insects. The altar was thirty-six inches high and eighteen inches in both length and breadth (Exodus 37:25ff). It served as a place for the daily burning of incense, both morning and evening.
The daily exercise consisted of a priest (selected by the casting of lots) taking burning coals from the brazen altar of sacrifice out in the temple court, taking the coals to the altar of incense, and depositing the incense upon coals (Exodus 30:7-8). This was a one-time event in the life of the priest who was selected.
Incense was also utilized on the Day of Atonement Lev 16:29
And this shall be a statute for ever unto you: that in the seventh month, on the tenth day of the month, ye shall afflict your souls, and do no work at all, whether it be one of your own country, or a stranger that sojourneth among you:
The 'course of Abia or Abijah' is the time signature as to when the miraculous conception of John the Baptist took place. On or about the 23rd of Sivan or June 23-24 by our calendar. Six months later the Divine Conception of our Lord and Savior took place.
Peoples during the course of history have had a must need to muss with dates and times to fit their traditions.
As a historical note taxes and census taking did not take place in the 'dead' of winter, but at the end of harvest. That would be around the Feast of Tabernacles, and the literal time of the year Christ was birthed. It is really toooo bad and sad how much modern Christianity ignores the so called Old Testament.