At the moment of time we see as “the end of our lives,” God has done everything He will. If you’re imagining something like this:
Billy is born. God sees his life and that he chooses hell. God gives grace until the future moment changes to Billy going to heaven.
then that’s not what I’m talking about. The future already exists, has “already happened” in the mind of God. He also doesn’t see the future then do what’s necessary to get there. He sees the end result of His actions and ours at the same moment as we are created. It’s a logical impossibly to say that God could change a future that exists because of His actions. God cannot do the logically impossible, like make a square circle, a married bachelor, or change a future He made.