The plain meaning of the language is that the events of Revelation began to come to pass shortly after John received the vision. (Introduction, pg. 1.) What is meant by plain meaning? How should Scripture be interpreted?
“The grammatical and historical interpretation of the Apocalypse, as well as of any other book, is the only safe foundation for all legitimate spiritual and practical application.”
Philip Schaff, History of the Christian Church, Vol. 1, p. 698.