In your 11/24 post Let's take a close look at December 1, 2025, as the potential date to start the 2520-day Tribulation you asked when is the next sabbatical year.  According to the article at When is the next Sabbatical year? - Chabad.org the year 5789 on the Jewish calendar (Sept. 20, 2028–Sept. 9, 2029) will be the next Sabbatical year. A Sabbatical year is always the 7th year which is a year of rest. If the tribulation period is actually 7 years long, it is more likely that it would begin in the 1st year of the 7 year period called a week of years and end in the 7th year Sabbatical year which is a year of rest. The article at What Is Shmita, the Sabbatical Year? | My Jewish Learning also states that the next sabbatical year begins on Sept.20, 2028.

The last sabbatical year or 7th year was 5782 which was 9/06/2021 through 9/25/2022. 

An article published by J.R. Church on Sept. 1981 called Sabbatical Year | Prophecy in the News states "there was a widespread belief in ancient Judaism, that the coming of the Messiah, would take place during the season when Israel celebrated the sabbatical year."