Satan was initially created as good, not evil.
In the Bible, the phrase "the heavens" includes living heavenly beings. This means that, in the beginning, GOD created the living beings who dwell (or dwelt) in the heavens.
Satan was one of these heavenly beings and, thus, was created when the rest of "the heavens" were made.
At the end of the six-day creation week, GOD pronounced that everything was "very good."
This means that Satan was initially created as good. And that implies that GOD is not the creator of evil. Jesus affirmed this:
44 You belong to your father, the devil, and you want to carry out your father’s desires. He was a murderer from the beginning, not holding to the truth, for there is no truth in him. When he lies, he speaks his native language, for he is a liar and the father of lies.
(John 8:44 NIV)