Well, I don’t get hung up on that number, see it allegorically referring to the Pagan Roman Emperors who were persecuting the early Church and it also prefigures anyone who persecutes the Church and those who believe in Christ. And all of those people who have and will do those things are led by the Deceitful one which could also refer to the Devil leading people away to apostasy.
I don’t think my personal views here are in-consistent with official Catholic Doctrine, but to be honest, millennialism is not one of my favorite theological subjects, so I may be off on a few points and if so, I will converge my views on the subject with what is taught officially.
If you are following Roman Catholic doctrine then you would not have to be concerned about millennialism. The Roman Catholic church primarily holds an amillennial replacement theology position for eschatology.