Wanted to add a link I just came across this morning with a little snippet of text relating to 3 days of darkness..

[link to www.his-forever.com]

"Peter’s prophecy that states “The sun shall be turned into darkness, and the
moon into blood, before that great and notable day of the Lord come,” has not
been fulfilled at any time in this present dispensation and you readers know it. Then if this prophecy is to be fulfilled in this present dispensation, like the rest of his prophecy has been, then it must be fulfilled before the Lord comes to resurrect and rapture His people to glory. "

"If the whole entire earth is plunged into darkness for three days, then it will be as the blackness of “night” over the whole earth during that entire time. Peter’s prophecy will be fulfilled to the letter. Paul’s “pattern” will be fulfilled. The types and shadows set forth in the Old Testament will be fulfilled, and our Lord will literally come “as a thief in the night” to resurrect and rapture His people to glory. "

Much more at the link above.

And, here is more info on the importance of Rosh Hashanah and it's possible relation to end times prophecy fulfillment...

[link to www.hebroots.org]

"The gates of Heaven are opened on Rosh HaShanah so the righteous nation may enter (Isaiah [Yeshayahu] 26:2; Psalm [Tehillim] 118:19-20). Because the gates of Heaven are understood to be open on Rosh HaShanah, this is further evidence that the rapture (natzal) of the believers in the Messiah Yeshua will take place on Rosh HaShanah."