The Hebrew marking of Abib as the first month of the year at the time of the Exodus was not the beginning of counting time by months, for notice the reading of Exodus 12:2, “This month shall be unto you the beginning of months”—they already had months, of which this was to be known as the “beginning.”
In Noah’s time, when the flood was receding, people were measuring time in months. Genesis 8:14 records, “And in the second month, on the seven and twentieth day of the month, was the earth dried.”
Genesis 7:11 also records the measuring of time in months: “In the six hundredth year of Noah’s life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened:” They were measuring time in months, and this was approximately 2400 years before Christ.
There is yet one more detail we may discover from this bit of Genesis history: a month consisted of about 30 days. Genesis 8:3 records that at the end of an “hundred and fifty days the waters were abated.” We read also that the flood began in the second month, on the seventeenth day (Gen. 7:11) and that the waters “were abated” in “the seventh month, the seventeenth day.” This defines a period of five months, the same period described as 150 days in Genesis 8:3, showing us that the length of a month was 30 days.
In the days of King David, as recorded in 1 Chronicles 27:1-2, about 1060 B.C., months were used as a measurement of time. We read:
“Now the children of Israel after their number, to wit, the chief fathers and captains of thousands and hundreds, and their officers that served the king in any matter of the courses, which came in and went out month by month throughout all the months of the year, of every course were twenty and four thousand. Over the first course for the first month was Jashobeam the son of Zabdiel: and in his course, were twenty and four thousand.…” There were 12 captains, one for each month of the year, a fact which shows that they were counting 12 months to the year.