In reply to your 8/30/2029 post caled Revelation 1:1 Tells Us Everything at http://www.fivedoves.com/letters/aug2020/garryb830-1.htm at http://www.fivedoves.com/letters/aug2020/garryb830-1.htm , there aren't always 1,260 days from Nisan 10 through the Feast of Trumpets because the Jewish calendar sometimes contains 2 months of Adar instead of 1 before the Month of Nisan. These 2 months are called Adar 1 and Adar 2.

In your post you also stated "The next Nisan 10 on God's sacred calendar is April 21, 2021" which is incorrect.  Nisan 10 in on 3/23/2021, and  3/23/2021 through 9/02/2024 is 1,260 day which is not the Eve of the Feast of Trumpets.  From Nisan 10 on 3/23/2021 through 10/02/2024, the Eve of the Feast of Trumpets is 1,290 days.  Here is the Jewish calendar showing Nisan 10 as 3/23/2021:  https://www.timeanddate.com/calendar/monthly.html?year=2021&month=3&country=34

Nisan 10 is on 4/11/2022 through 9/21/2025 is 1,260 days, but it is the day before the Eve of the Feast of Trumpets which begins on 9/22/2025 on the 1,261st day.

Nisan 10, 4/01/2023 through 9/11/2026, the Eve of the Feast of Trumpets is 1,260 days.

Nisan 10, 4/18/2024 through 9/29/2027 is 1,260 days, but the Eve of the Feast of Trumpets is on 10/01/2027 which is the 1,262nd day.

Nisan 10, 4/08/2025 through 9/18/2028 is 1,260 days, but the Eve of the Feast of Trumpets is on 9/20/2028 which would be the 1,262nd day.

Nisan 10, 4/17/2026 through 9/07/2029 is 1,260 days, but the Eve of the Feast of Trumpets is 9/09/2029 which would be the 1,262nd day.

Nisan 10, 4/17/2027 through 9/27/2030, the Eve of the Feast of Trumpets is 1,260 days.

Nisan 10, 4/10/2028 through 9/22/2031 is 1,260, but the Eve of the Feast of Trumpets is 9/17/2031 which would be the 1,255th day.

Of the 8 examples above, only 2 out of 8 are 1,260 days from Nisan 10 through the Eve of the Feast of Trumpets so there are not always 1,260 days from Nisan 10 through the Eve of the Feast of Trumpets.