I am going to present here why we must keep the jewish popular calendar in front of us if we are going to discern when Jesus will come for us, because God will indeed use it.
Keep in mind that when I refer to the popular jewish calendar, I am also referring to the framework for knowing the correct nations' calendar because they are synced together, though offset by 6 months.
Does the above mean that we are not to discern if the popular jewish calendar is inaccurate in a given year? Not at all. Doing so actually is also a benefit to seeing when Jesus may come for us, because we will see a timing-line-up of types/shadows on both, as long as keep both calendars before us. My point of this post is that we must do this.
We greatly error when we think that we must choose between the two. What I am saying is that if the jewish popular calendar is indeed off by one month, for example, in a given year, then if Jesus does come for us in that year, the timing will dovetail both calendars. God will NOT negate the children of Israel's God-given, authoritative place to establish the calendar. In Leviticus 23:2, God makes it clear that the sons of Israel are to proclaim the Feasts and by inference, the calendar itself. The nations do not have the right to subvert this position of responsibility. (In the millenial kingdom, God's earth-based kingdom will be centered in Israel and He will rule the nations through them. We in the body of Christ will assist them to fulfill their leadership and priestly roles, but we will not replace them in those roles. The kingdom of God we inherit is of the heavenly places (Eph 1:3), taking over, in part, the places that Satan and his minions had occupied prior. Once they get kicked out and thrown down to only inhabit the earth realm for a limited time, prior to their wrath judgment by Jesus, then we take their place.)
Now, in terms of the body of Christ, who are New Creations because of our union with Jesus, and in which there is neither Jew nor Gentile, are we to be concerned if Israel is indeed a month off in a given year? No, because our trust is in the Great I Am, and we know that even when Israel is a month off, He will simply fulfill a type/shadow for taking us home on BOTH the popular jewish calendar AND the correct calendar, which I believe is the very thing He is about to do. So, we honor Israel's God given place to establish the calendar by our keeping their calendar in front of us while at the same time keeping before us the correct calendar, and looking for the "dovetailing" of the timing of us going home being fulfilled on BOTH. We are NOT to negate Israel's popular calendar in our watching. When we humbly honor Israel's God-given responsibility, we are actually given more timing clues!
Why do I hold so firmly to the above? I observe a number of events in Israel's history that support how serious God is about others honoring the God-given positions of those God has given responsibility to.
Think of how God dealt with the rebellion against Moses and Aaron's God given positions of leadership led by Korah? The earth opened up and swallowed them alive.
Think of how God dealt with the rebels who opposed Moses and Aaron after the death of Korah's group? 14,700 died. It would have been many more if Moses and Aaron had not rushed to intervene.
Think of how God dealt with Aaron's and Miriam's attitude against Moses? Miriam's leprosy not only meant she was going to be put out of fellowship from within the community, it was also going to unfold as an early death sentence for her if Moses had not interceded.
Think of when the Syro-Phonecian woman approached Jesus directly for a miracle. Jesus said, "No." It was only after she expressed her understanding that her place was under Israel in God's earth-based kingdom that Jesus then granted her request, praising her faith.
Now, think of the positive example of David. He was annointed king by Samuel. As David became older, the nation was not doing well under king Saul. Saul even hunted David to kill him. When David had the perfect opportunity to "make things right" by killing Saul in the cave, what did David do? He humbled himself before God and did not harm the person God had annointed to be king, even though that man was royally messing things up. David would wait on God's timing to exalt David to the throne.
So, in my thinking, since God gave the sons of Israel the responsibility to determine the calendar, I do not have the right to blow it off simply because I sincerely believe it is not accurate. God will use it AND the correct one, both at the same time.
When will Israel's calendar be restored to accuracy? When God's appointed "restorer", Elijah, shows up to correct their calendar. In the mean time, I keep it before me. I have come to discern that if a particular brother or sister presents a high watch date yet are ONLY referencing what they believe to be the "correct" calendar, and (even sincerely so) NOT also able to reference the popular jewish calendar in some way (in terms of the timing of types/shadows), then I cannot automatically place a great deal of weight on what they present until, at least, I am eventually able so see how the date they are watching also has a "dovetailing" fulfillment per the popular jewish calendar.
I believe one reason the Father will time when we go home per the jewish popular calendar (and why He still wants us to reference it in our watching) is in order to provoke the Chosen Remnant in Israel-Judah to jealousy. Part of this will be accomplished by their identifying our going home with the timing of a type/shadow fulfillment according to their popular calendar, even if it is the fulfillment of the type/shadow of the Mount Sinai event (this time for the bride of Christ from out of the nations) on the "offset by 6 months" nations calendar, on the nations' 17th day of the 3rd month, or Israel's 17th day of the 9th month.