How was that rest prepared?God prepared a place of rest for those that would believe in Him. We see this in both the OT and NT.
God being omniscient knew that man would try to do it his own way and provided the means for man to restore his broken relationship with God. Whether through faith in the OT or faith in the NT it is still faith in God.
Creation was not for the cross, it was for man so they could have a relationship with God.