rereading Dan ch 9 "covenant with many" this seems to me to say the AC is one of many confirming or agreeing with the treaty
As I have said, I think the AC is initially at the beginning of the trib an also-ran, He only becomes "somebody" at the mid-point of the tribulation when he gets power from the world leaders to rule 42 months; 3 1/2 years........
When the AC assumes supreme power the first thing he does is stop the temple sacrifices
its another 1290 days until he kills the 2 witnesses, profanes the temple(abomination of desolation) and Armageddon begins