Psalms 81:3 Blow up the trumpet in the new moon, in the time appointed, on our solemn feast day.
Psalms 104:19 He appointed the moon for seasons…
In Hebrew, Rosh Chodesh means, literally, “head of the month” or “first of the month.” Rosh Chodesh is the first day of any new month. In ancient times, Rosh Chodesh was a significant festival day.
The day after the new moon appeared was a festival, announced with the sounding of the shofar, commemorated with solemn convocations, family festivities and special sacrifices. Rosh Chodesh is an expression of First Fruits. It is an opportunity to sanctify the month, your time and your money.
He also gave us three ways to honor Him with our substance the Tithe the offering and First fruits.
The Prophetic Calendar by Dr. Howard Morgan (Audio Teaching)