Rosh Chodesh, is the head or beginning of each new moon, making it the beginning of each month.
Leviticus 23:4, gives the instruction. Notice the phrase, “holy convocation”. This statement in Hebrew is mikraw kodesh, and is also translated, “holy convocation and rehearsal”. So, God’s appointed times are
actually the “holy rehearsals” set apart to reflect events in the Messianic kingdom.
This is the seeming understanding of The Apostle Paul when he states that the
Sabbaths , new moons and festivals, “are a shadow of things to come; for the body
of Christ ” (Colossians 2:17).
Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day— things which are a mere shadow of what is to come; but the substance belongs to Christ.
In the spring and fall, there were scheduled several appointed times of holy convocation dedicated to the Lord. The new moon in ancient times was the sign allowing the fulfillment of those set feasts, which were the holy convocations and
rehearsals for a future time.
The new moon would be
announced on the first day of Tishri to begin the New year and Rosh Hashanah, the people knew
That this set the time for this observance.
“Speak to the sons of Israel, saying, ‘ In the seventh month on the first of the month you shall have a rest, a reminder by blowing of trumpets, a holy convocation.
The announcement of the new moon triggered the festival dates which followed.
In ancient times the calendars did not list the feast days, the Sanhedrin were responsible for determining the timing of the new moon each month to allow the Feasts to proceed. They did this with two independent witnesses. They had in Jesus time and before a stable of witnesses. They treated these very well so that they would do their job and report in to the Sanhedrin each month. They were important, because all of the observances of Israel road on their testimony. They were given special privileges so that they were immune to the Jewish Sabbath travel restrictions.
Rosh HaShanah Chapter 2, Mishnah 5 reads: There was a large court in Jerusalem called Beth Ya’azek. There all the witnesses used to assemble and
the Beth Din used to examine them. They used to entertain them lavishly there so that they should have an inducement to come.
The first two to agree on the details of the sighting would bring the confirmation that the new month had begun. At that time torches were lit atop the high places to announce across the land that the new moon had been sighted. And the Feasts days were established.
The month Tishri was the appointed time called Rosh HaShanah, the Feast of Trumpets
Leviticus 23:24. This is the only appointed feast by God to occur on the first day of a month. Therefore the moon siting was of extreme importance. The festival could not begin until its siting and communication. Thus no man knows the day or the hour. This feast represents to Israel the coming of their king, and to us the new millennial kingdom.