Your thoughts on Rosh Hashanah (No man knows the day or the hour) being the likely day that the Lord will set up His kingdom on earth has me studying the 7 Feasts in detail. I know that you are not setting dates but I have been really trying to understand the prophetic math for the next decade.
I think the Lord will likely return on Rosh Hashanah. 10 days later He’ll judge Israel on Yom Kippur. 20 more days will be required to gather and judge the nations (Joel 3:1-2) bringing the total to 30. Another 45 days will be needed to cleanse the Temple, install the priesthood, and set up the Kingdom. This is consistent with the reference in Daniel 12:11-12 to 1290 days and 1335 days.
As for more specific timing, we’ve narrowed it down close enough for my comfort level. Any more and we’ll be getting into the overlap of Gregorian years vs. Jewish ones, and whether the Lord counts a year as 360 days or 365. And none of this will tell us anymore about when to expect the Rapture. It could come any day.