so time as we know it would have started then.
Time is part of God, maybe.
I understand time as the length between 2 events or change. Time existed with God before the universe. There was a point in time when only the King of Eternity existed. But as the scripture pointed out God changes time and seasons inside the universe so time inside the universe doesn’t govern God but God governs time according to one interpretation of the verse, making time proscriptive whereas God is descriptive defined by his fundamental qualities and other descriptions too —maybe one of those descriptions is time too.
If it makes any sense God’s existence by himself is not idle. He is alive and active and there is a length of time between one aspect of his existence compared to another. So, I suppose it is possible to measure length of time in heaven using a physical standard counting back in time: a google to the google power years from the time God created Jesus to the time God felt something all by himself or between two other events inside God’s mind or person. As someone brilliantly posted, God experiences the same time we do differently.
No matter how you cut it though, 108 years of Satan after 1914 is not a short period of time if people are expecting change compared to one’s lifetime.