This is very simple to understand as God's grace is sufficient for us all to understand His word.

These 3 events from 2010-2015 of Revelation 6.12 that usher in to produce a 2,520 day period as required for 2015 to 2022 has a likelihood of occurrence of 1 in 112,000,000,000,000.

Rev. 6.12 occurs right before the first rapture "before the throne" (Rev. 7.9) that is according to readiness (3.10) before the 1st trumpet (8.7) of the Tribulation that begins the 7 year Tribulation.