I think it really is O.K. not to try to answer the question of when this war arose. The point of the vision is not to identify the point in time when this happened, the point is to identify the great spiritual conflict between Satan and his angels, that is the demons, and Michael who has a great military made up of angels.
The Triumph of the Lamb: Vol 3: Dr. Neufeld’s third volume on the book of Revelation. A study of chapters 12-17. Specifically, we examine the 7 significant visions that are presented in this portion of scripture. Visions that give a sense of what the present spiritual warfare and future warfare of the church is all about.