I don't hold to things that rigidly on what is not explicitly given in the bible.
The Bible nowhere explicitly states that God’s foreknowledge is after conversion.
The Bible nowhere states that predestination is an act of God that follows conversion.
The Bible nowhere states that God foreknew a corporate group but did not foreknow individuals.
The Bible nowhere states that God’s eternal purpose changed after He created the world. Which is why your argument that God foreknew from the foundation of the earth somehow means that He did not have the same eternal purpose before the foundation ( ie in eternity) a strange argument.
Etc.