"God is not limited by time. With him there is no present, past and future, but one eternal now. He knows all things from the beginning." (J. Clyde Turner, These Things We Believe).
God knows all that is past, present, and future. What God knows now about the future is revealed in Bible prophecy. Our knowledge is limited. The knowledge of God is unlimited.
God knows all things simultaneously. Our knowledge is limited by time and space. God is omniscient knowing the end from the beginning (Acts 15:18). We know in part and only in part. God knows all things now.
God knows the names and exact number of all who shall be saved. They are now justified and glorified in Christ as far as the knowledge of God. The apostle Paul wrote of God's foreknowledge in terms of prolepsis, knowing the future now as already accomplished (Romans 8:29-30). Yet, God's command is for all people everywhere to repent (Acts 17:30; 2 Peter 3:9).
God knows all who shall be in Christ. That includes all who will repent and believe the gospel (Acts 2:38; 13:48; Ephesians 1:4, 13). God turns none away who will repent and believe on our Lord Jesus Christ (Acts 16:30-31). Yet, God knows now all who shall be saved in Christ (1 Peter 1:2).