In Rev 1:11, Christ is said to be the alpha and omega, the first and the last. He is also the “Word,” so that it supports the Rule of 1st Use--where a word or phrase is first found, it often has a context that we should understand for the end-time (omega).
John heard a great voice as of a trumpet. The first place we find “trumpet” in the Bible is Exodus 19, when God came down on Mt Sinai. It was a mini-Judgment Day, The mountain shook and everyone was afraid. [“Fear God…time of His Judgment” Rev 14:7]
Here a video with more https://www.youtube.com/watch?v=PBSJQsHrF_k
Here's a video with a 2nd key insight to Revelation 1 at https://www.youtube.com/watch?v=lW_ODaMtg9U
Dr. Richard Ruhling is an author on current events and Bible prophecy.