Devout Christians: When To Expect The Two Witnesses, Part 1 of 2. : ThyBlackMan.com
It was a yearly rehearsal for the expectation of the coming of the Messiah. It was prophesied that the Messiah would ride into Jerusalem on that day (see Zechariah 9:9). That is why the people were there to acclaim Yeshua when He rode in on Saturday April 24th AD 28. Four days before every Passover, this would occur. In a similar manner, seven days before Passover, the two witnesses are to appear. It is because their prophecy against the anti-Messiah is to last 1,260 days, which is exactly 180 weeks. How did we suddenly come to this conclusion? We will explain that in part two.
Source: thyblackman.com