To Jennie – No One Knows.  See my Post “Jubilee 2017”
Elijah new when he was going, he knew the day but it didn’t look he knew the hour. All the prophets around him also knew what day he was going.
So many people have a mind-set that “No one knows” that I believe it has stopped God from being able to tell them.
That day “the unknown day” is Rosh Hashannah the unknown day because the new moon has to be sighted before, by law, the day can be called or started.  Yes no one knows this day and because of this the days following could be later than the calendar set dates.
I believe that Rosh Hashannah “The unknown day” itself is the day of the second coming, not the Rapture but the second coming of Jesus back to earth with us his saints – what a glorious day that will be.