There are many who actually believe that the Sabbath year begins with the seventh month of Tishri and not with the first month of Abib (Nisan).
It has also been extrapolated by many that not only should Sabbath years commence according to a Tishri reckoning but that every year should begin with the seventh month of Tishri.
If one believes that such a notion is found in Scriptures, then it is suggested that one take a closer look at the relevant facts of the matter.
In order to addess this issue we must contend with the concept that the Jews, from the time of their return to Judaea from Babylon in 538 B.C.E. until the end of the Bar Kochba revolt (135 C.E.), officially began their Sabbath years with Tishri 1 (Sep./Oct.) of the sixth year of the Sabbath cycle, as had become their custom sometime after the Bar Kochba war.