Paul,
Yahusha (the Messiah) told John what to write to the churches in the Book of Revelation. That includes the sign of The Woman in Revelation 12:1-2.
He may not have known the timing of his second coming before he was killed and brought back to life. However, I believe that he knew the timing when he made his revelation to John many years later.
He also gave our generation computers and an understanding of celestial mechanics. We can know with certainty the timing of the sign of The Woman. It is simply a matter of putting the puzzle together.