Dear Spoely
You asked a very good question:
Maybe there is a satisfying explanation:
In a Jubilee year, Rosh Hashannah is shifted and falls on the SAME day as Yom Kippur. The following article explains it:
So if the rapture happens at Rosh Hashannah prior to the great trib, the people left behind will have to wait till the final day when Jesus returns, which is Yom Kippur, and because Jesus will return in the Jubilee, it will be the exact same day in that year as Rosh Hashannah.
So maybe Rosh Hashannah will have a double fulfillment or it will be fulfilled only once with the pre-great-trib rapture.
In case that the rapture does not happen at any Rosh Hashannah prior to the great trib, I fully agree with you that it most likely will be fulfilled only once, and that is at the end of the great trib when Jesus returns. My best bet for that is still 23. Sept. 2015. If this end date turns out true, then Rosh Hashannah becomes the ultimate Rapture-Rosh, and the rest of the timeline can only be fulfilled correctly due to the "shortening of days".
Maybe you also want to have a look at my recent post "All lines up at Rosh Hashanah 2012 & Yom Kippur 2015":
Watch & Pray!Keep looking up!Maranatha!Be ye Ready!Shalom!
YBIC, Josua