Satan fell. (Isaiah 14:12, Ezekiel 28:11-19). We do not know when, because the timeline for God’s creation of the universe and all its beings (including angels) is not specifically mentioned in scripture. We know that they were already created when God created the world, because they praised God for it. (Job 38:6-8). We know none of them had fallen by the conclusion of the sixth day when God saw all that he had made, and declared it very good.
By the time Genesis 3 came, though, satan was a fallen, evil, sinful creature. Revelation strongly intimates that he caused a third of his cohorts to fall with him. (Revelation 12:4).
However as we see from today’s verses in the Bible Reading Plan, satan and his cohorts to this day still have access to heaven. They still appear to God. They still stalk the heavenlies and strut in the holy place. God allows this for His sovereign purposes. In another example separate from today’s, we see that God used a lying spirit to deceive Ahab, (2 Chronicles 18:18-22). Satan and hsi demons come and go in heaven.
One day, and what a day that will be, God will SHUT the door of heaven and satan and his third of hosts will not be granted access to heaven any longer. This will occur in the Great Tribulation, as depicted in Revelation 12:7-17. In fact, this rejection enrages the devil so much that he redoubles his efforts to overcome God’s people and His kingdom. The persecutions and evil events already occurring on earth at that time turn to massive and horrific evil as many millions of believers are martyred. Revelation 12 again.
Whether satan is presenting himself before God in heaven or tormenting His people on earth, whether it is the Great Tribulation or just nowadays, God is fully in control. You see in the verses in Job that God set limits to satan’s actions, and satan adhered to them.
God is sovereign, and if you are a believer in Him, with the Holy Spirit in us as a seal of His guarantee of redemption and eternal life, you have already overcome the devil- because Jesus did.
He disarmed the rulers and authorities and put them to open shame, by triumphing over them in him. (Colossians 2:15)