Satan’s fall from heaven is symbolically described in Isaiah 14:12–14 and Ezekiel 28:12–18. While these two passages are referring specifically to the kings of Babylon and Tyre, we believe they also reference the spiritual power behind those kings, namely, Satan. These passages describe why Satan fell, but they do not say when the fall occurred. Jesus, the eternal Son of God, witnessed Satan’s fall, and He mentions it in Luke 10:18: “I saw Satan fall like lightning from heaven.” We know that the angels were created before the earth (Joeb 38:4–7). Satan fell before he tempted Adam and Eve in the Garden (Genesis 3:1–14). Satan’s fall, therefore, must have occurred somewhere after the time the angels were created and before he tempted Adam and Eve in the Garden of Eden. Whether Satan’s fall occurred hours, days, or years before he tempted Adam and Eve in the Garden, Scripture does not say.
The book of Joeb tells us, at least in Joeb’s time, Satan still had access to heaven and to the throne of God. “One day the angels came to present themselves before the LORD, and Satan also came with them. The LORD said to Satan, ’Where have you come from?’ Satan answered the LORD, ‘From roaming through the earth and going back and forth in it’” (Joeb 1:6-7). Apparently at that time, Satan was still moving freely between heaven and earth, speaking to God directly and answering for his activities. Whether God has discontinued this access is a matter of debate. Some say Satan’s access to heaven was ended at the death of Christ. Others believe Satan’s access to heaven will be ended at the end-times war in heaven (Revelation 12:7–12).

Why did Satan fall from heaven?

Satan fell because of pride. He desired to be God, not to be a servant of God. Notice the many “I will...”   statements in Isaiah 14:12-15. Ezekiel 28:12-15 describes Satan as an exceedingly beautiful angel. Satan was likely the highest of all angels, the anointed cherub, the most beautiful of all of God’s creations, but he was not content in his position. Instead, Satan desired to be God, to essentially “kick God off His throne” and take over the rule of the universe. Satan wanted to be God, and interestingly enough, that desire is what Satan tempted Adam and Eve with in the Garden of Eden (Genesis 3:1-5).

How did Satan fall from heaven? Because of Satan’s sin, God cast him out of heaven (Isaiah 14:15; Ezekiel 28:16–17). Heaven is no place for the wicked one. Satan fell from heaven because he was pushed.

https://www.gotquestions.org/Satan-fall.html

Isaiah 14:12-15

NIV

 How you have fallen from heaven,
    morning star, son of the dawn!
You have been cast down to the earth,
    you who once laid low the nations! You said in your heart,
    “I will ascend to the heavens;
I will raise my throne
    above the stars of God;
I will sit enthroned on the mount of assembly,
    on the utmost heights of Mount Zaphon.^[a] I will ascend above the tops of the clouds;
    I will make myself like the Most High.” But you are brought down to the realm of the dead,
    to the depths of the pit.

Ezekiel 28:16-17

NIV

 Through your widespread trade
    you were filled with violence,
    and you sinned.
So I drove you in disgrace from the mount of God,
    and I expelled you, guardian cherub,
    from among the fiery stones. Your heart became proud
    on account of your beauty,
and you corrupted your wisdom
    because of your splendor.
So I threw you to the earth;
    I made a spectacle of you before kings.

What did it mean that Satan wanted to be like the Most High in Isaiah 14:14?

Many interpreters, including some early church fathers, saw a secondary reference to Satan’s fall from heaven (Luke 10:18; this view is the basis for John Milton’s famous confrontation between Satan and God in Paradise Lost). In this interpretation, “I will ascend above the tops of the clouds; I will make myself like the Most High” also represents Satan’s ambition to overthrow God. Assuming a secondary reference to Satan in Isaiah 14:14, why was it a sin for Satan to want to be like God?

In the context of Isaiah 14, being “like the Most High” does not mean “being like God in character or attitude.” Isaiah 14:12–15 is talking about an attempted coup, a desire to surpass God. Verses 13–14 are laden with ancient Near Eastern images of divine dominance and power, including stars, mountains, and clouds. The speaker wants to be like God in power and authority. He wants to wield ultimate cosmic power, even over God Himself. Simply put, he would like to be God, ruling the universe with unopposed might.

A desire to be like the Most High in holiness and righteousness is not evil but is encouraged by the Scriptures (Ephesians 5:1–2). But a craving to have God’s power and authority is evil, stemming from the depths of depravity (Proverbs 16:5). God is incomparably great (Psalm 145:3), so it is irrational to attempt to surpass Him. He alone is God, so it is irrational to attempt to be God. The only reason a creature would want to become its Creator is due to a warped, prideful sense of self-importance. Selfishness, envy, and pride drive rebellion against the perfect Creator. It is a sin for Satan to attempt to be “like the Most High” in glory and power because it is a pointless attempt fueled by selfish ambition and pride.

Thankfully, Satan’s rebellion against God is futile. God remains enthroned over the cosmos (Isaiah 40:12-31). Satan is in no way comparable to God because God is incomparably awesome (1 Chronicles 29:11; 2 Timothy 1:7; Colossians 1:16; 1 John 5:18–19). God’s power has no match, and He has no equal. He is the perfect King and governs the universe with righteousness and love (Mark 10:18; Isaiah 28:28; Romans 11:33; Psalm 100:5; 1 John 4:8). Satan’s plans have already been defeated, and he will be subject to eternal torment for his sins (John 12:31; 16:11; Colossians 2:15; Hebrews 2:14; Revelation 20:10). “This is what the Lord says—Israel’s King and Redeemer, the Lord Almighty: I am the first and I am the last; apart from me there is no God” (Isaiah 44:6

With Permission:

https://www.biblestudytools.com/bible-study/

Paradise Lost, John Milton, as stated in “Got Questions”