Not now. When they first began to rebel.
And, like Pharaoh.... they hardened their hearts.
And have you completely forgotten this word of encouragement
that addresses you as a father addresses his son?
It says,
“My son, do not make light of the Lord’s discipline,
and do not lose heart when he rebukes you,
because the Lord disciplines the one he loves,
and he chastens everyone he accepts as his son.”
Hebrews 12:5-6
Angels were called "sons of God."
Satan began a rebellion amongst the angels.
God disciplined them in attempt to get them to repent, especially Satan, while it was yet the time of determination of their volition. Like with Pharaoh, the time and tries was brought to a head.