The Lord Jesus said the following from heaven:
"And, behold, I come quickly; and my reward is with me, to give every man according as his work shall be" (Rev.22:12).
What "coming" was He referring to and did He come quickly?
He was referring to His second coming, His return to establish His kingdom on Earth.
So the Lord Jesus said "I come quickly" but He hasn't come yet?
Correct. And He meant it.
Why?
Jeremiah 18.
Circumstances changed. He fully intended to return within 7 years of his resurrection. One year into that, however, and Israel wasn't showing any fruit from the Holy Spirit's fertilizing.
So God cut off Israel (temporarily), and grafted in the Gentiles to work with them, putting Israel's plans on hold "until the fullness of the gentiles has been reached."
God said He would establish Israel, they rebelled, so He couldn't.