Another issue you should resolve in order to understand this better is...
...when are men placed in the Book of Life?
I would suggest to you that all men are in the Book of Life, and that the "Lamb's Book of Life" is specific to those who are saved, but, does not detract from the general principle taught in Scripture that men are in the Book of Life, and are blotted out depending on their obedience to God's will.
I don't think this is relevant to the issue, but what you're describing is impossible. John says that ALL people on earth, EXCEPT those written in the book of life from the foundations of the world, will worship the beast.
Rev 17:8 "The beast that you saw was, and is not, and is about to rise from the bottomless pit and go to destruction. And the dwellers on earth whose names have not been written in the book of life from the foundation of the world will marvel to see the beast, because it was and is not and is to come."
Rev 13:8 "and all who dwell on earth will worship it, everyone whose name has not been written before the foundation of the world in the book of life of the Lamb who was slain."
So it's not possible that EVERYONE starts out written in it; that would mean NOBODY would worship, because none of them were NOT written from the foundation.
However, again, I don't think this actually is relevant -- it's just that you seem to think it is.
They are not written in the Book of Life from the foundations of the world the same way these...
Matthew 25:34
Then shall the King say unto them on his right hand, Come, ye blessed of my Father, inherit the kingdom prepared for you from the foundation of the world:
Was the Kingdom already in place? We know He is not speaking about the spiritual Kingdom all believers enter into upon salvation, but it is either the Millennial Kingdom or the Eternal State. Seeing that Christ went to prepare that place for us when He returned to Heaven, the most probable Kingdom in view is the Millennial Kingdom, which fits within the framework of the Covenant of Law, which is what Christ ministered under.
Ephesians 1:4
According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love:
Again we see the foreknowledge of God. But we know that it is not fulfilled until each individual is born and comes to saving faith in Christ.
Hebrews 4:3
For we which have believed do enter into rest, as he said, As I have sworn in my wrath, if they shall enter into my rest: although the works were finished from the foundation of the world.
So when did the Rest of Christ become available? It was not when they entered into the promised land, but when men began entering into Christ Himself. Yet this is viewed as finished from the foundation of the world.
1 Peter 1:20
Who verily was foreordained before the foundation of the world, but was manifest in these last times for you,
Again, we see something from before the foundation of the world fulfilled at a later time.
Revelation 13:8
And all that dwell upon the earth shall worship him, whose names are not written in the book of life of the Lamb slain from the foundation of the world.
Again the foreknowledge of God is in view, and this is a statement that marks the certainty of their destruction. Again...can't be blotted out of the Book of Life if you were never in there, and every single member of the lost will be blotted out.
God bless.