HOW DO WE KNOW THAT NOAH COUNTED THE MONTHS STARTING IN THE FALL?
There are two biblical facts showing the start of the year is in the spring. In Genesis 1:14-17, God gives the purpose of His heavenly orbs that were set to keep track of time. Verse 17 reveals that He set them in their starting positions, like setting a clock to the right time. Setting the heavenly clock accounted for the first day of creation, meaning that the sun and the moon would have to have the starting point to be the first day of the seven-day week—a Sunday.
Keeping this fact in mind and reading Exodus 12:1, a moon cycle that demonstrates this starting point can be found. By examining the thirteen 19-year time cycles of the moon there is only one that has the beginning day as the first day of the week. This can be confirmed in Chart 5 https://bit.ly/3pMHa2L, which shows the thirteen 19-year time cycles of the moon.
The seven-day creation account of Genesis and the statement in Exodus 12:1 forces the start of the year to be in the spring. Because Pentecost begins in the third month and represents the early spring harvest of the small grains, likewise the fall (or later harvest) is in the seventh month, The Feast of Tabernacles.
The Jews have a tradition that the creation occurred in the seventh month, but creation requires a starting day of the week as a Sunday. Again, by checking Chart #5, https://bit.ly/3pMHa2L which is the basis of the Jewish calendar, it is found that there is no cycle of the thirteen that has a first day of the week of the seventh month as a starting date.
The correct cycle is marked #1 in red (top left of page 2 https://bit.ly/3pMHa2L ) of the 13 cycles and reflects the correct beginning of the named day of the week—day 1.