Angel Uriel taught Enoch to count off God's Calendar Months in cycles of 30, 30, 31. He was also told that in future Mankind would err in the Calculations of the Calendar. I believe this error originates from observing the 1st Day of the Month after the New Moon when it should be observed on the Day after the Full Moon. 

If we calculate the Calendar the way Enoch was taught it means we're still yet to observe the Feast of Tabernacles! I believe this is the reason why the Rapture hasn't occured yet.

Day 1 of Month 1 May 11, 2017

Day 1 of Month 7 November 9 2017 -Trumpets

Day 10 of Month 7 November 18 2017 - Day of Atonement

Day 15 of Month 7 November 23 2017 - 1st Day of Tabernacles

Day 21 of Month 7 November 29 2017 - Last Great day.

Day 22 of Month 7 November 30 2017 - Sacred Assembly.