For the counting of years:
Rosh Hasannah, that takes place in September or October (varies), the Jewish month of Tishri, is the "head of the year", the start of the year. The Sabbatical year, the year of release. which is every 7th year in the 49 year cycle begins with Rosh Hashana.
For the numbering of months, i.e. 1,2,3, 4,5.......
That is based on commemoration from slavery to freedom in the liberation from Egypt is how the Jewish months came to be numbered with Nissan being month 1.
I got my information from this site...
therefinersfire.org
Here's an excerpt....
Counting years from Tishri (
Yom Teruah/Rosh Hashana) is also the date for calculating the release year (i.e., the "Sh'mittah" year, which means "Sabbatical" year, which is every 7th year in the 49-year cycle that governed the Kingdom of Israel [10th century B.C.E. to 8th century B.C.E.] and Kingdom of Judah [10th century B.C.E. to 6th century B.C.E.] in biblical times),
and the date for calculating the Jubilee year (a Jubilee year or "Yovel" year in Hebrew is the year after the 49-year cycle that governed the Kingdom of Israel and Kingdom of Judah in biblical times, i.e., the 50th year).
It doesn't matter what your opinion is. I get the actual information from the Law of Moses - the Scriptures.
[Exo 12:1-3 ESV] 1 The LORD said to Moses and Aaron in the land of Egypt, 2
"This month shall be for you the beginning of months. It shall be the
first month of the year for you. 3 Tell all the congregation of Israel that on the tenth day of this month every man shall take a lamb according to their fathers' houses, a lamb for a household.
[Lev 25:3-4, 8-10 ESV] 3 For six years you shall sow your field, and for six years you shall prune your vineyard and gather in its fruits, 4 but in the seventh year there shall be a Sabbath of solemn rest for the land, a Sabbath to the LORD. You shall not sow your field or prune your vineyard. ...
Sowing and pruning happen in the spring only. This confirms the years begin in the spring.
8 "You shall count seven weeks of years, seven times seven years, so that the time of the seven weeks of years shall give you forty-nine years. 9 Then you shall sound the loud trumpet on the tenth day of the seventh month. On the Day of Atonement you shall sound the trumpet throughout all your land. 10 And you shall consecrate the fiftieth year, and proclaim liberty throughout the land to all its inhabitants. It shall be a jubilee for you, when each of you shall return to his property and each of you shall return to his clan.
"The seventh month" is the fall season, at the Day of Atonement announcing the Year of Jubilee. It begins half way through the 49th year and extends into the 50th year.
[Lev 25:20-22 ESV] 20 And if you say, 'What shall we eat in the seventh year, if we may not sow or gather in our crop?' 21 I will command my blessing on you in the sixth year, so that it will
produce a crop sufficient for three years. 22 When you sow in the eighth year, you will be eating some of the old crop; you shall
eat the old until the ninth year, when its crop arrives.
It's very clearly stated that it is a 3 year process - eating the harvest from the 6th year (which God promises to make extra bountiful).
Spring 6th year - sow
Fall 6th year - harvest an extra bountiful crop
Spring 7th year - Sabbatical, no sowing
Fall 7th year - proclaim the Year of Jubilee, no harvest, no sowing
Spring 8th year - Year of Jubilee, no sowing
Fall 8th year - still Year of Jubilee, no harvest, sow winter barley
Spring 9th year (2nd year into next 7 year cycle) - Sow and prune like usual, begin regular harvest