In the mind and plan of God, Christ was the Lamb of God slain from the foundation of the world. (
Rev 13:8) The benefits of his blood and his sacrifice stretch forward into the day where we live, 2,000 years post-calvary. The benefits of that blood also went backwards into time to redeem the followers of Yahweh in the Old Testament. This same blood would also be the justification for those saved under the ministry of John the Baptist, but who died prior to Calvary. The blood will be the basis for everyone's redemption who make it into the glory world regardless of the time in which they lived. There's no redemption/salvation outside the blood of Christ.