Satan was loosed around the time Jesus appeared.
1 Chron. 21:1
"Now Satan stood up against Israel, and moved David to number Israel."
"Then he showed me Joshua the high priest standing before the Angel of the Lord, and Satan standing at his right hand to oppose him. And the Lord said to Satan, 'The Lord rebuke you, Satan! The Lord who has chosen Jerusalem rebuke you!"
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The word "sawtawn" in the Hebrew simply means "accuser." So 1 Chronicles should read, "And an accuser
stood up against Israel...." The "accuser" that stood against Israel was God
:"And the anger of the LORD was aroused against Israel and He moved David against them...." 2 Samuel 24:1
Job's "accuser" (sawtawn) was a man.
Psalm 109:6 simply means "accuser""Set a wicked man over him, And let an accuser stand at his right hand." NKJV
In Zechariah God was the "Adversary" (sawtawn) and the Angel of God (Christ) was Joshua's Advocate: " 1And he sheweth me Joshua the high priest standing before the messenger of Jehovah, and the Adversary standing at his right hand, to be an adversary to him." Young's Literal Translation
The translations which say "satan" are wrong.
Satan was bound throughout the old testament period. He was loosed for the "little season" between the two comings of Christ. It was not until then that we see satanic activity. He was judged in the first century and cast into the lake of fire.