In 2 Peter 3:9 Peter says is “One day is a thousand years, and a thousand years as one day.” Peter’s admonition is a quote from Psalm 90:4 where we read that, “For a thousand years in your sight are like yesterday when it is past, and like a watch in the night.” The point of this quote seems to be similar to Isa 55:8-9 “For my thoughts are not your thoughts, nor are your ways My ways, says the Lord. For as the heavens are higher than the earth, so are My ways higher than your ways, and so are My thoughts than your thoughts.”
We must always remember that we cannot by our very nature understand the mind of God! We instead must approach our discouragement with regards to what we perceive as “God’s delay,” not a problem with God but instead one of human perspective! There is an infinite qualitative difference between how God views time and how we do.