Jesus Christ "obtained", and was "perfected" in that He rose from the dead. Jesus Christ 'became' 'Lord', in that He rose from the dead - ultimately. He was called 'Lord' before; but since, He is Lord in perfection and through obtainment. Were He nor raised from the dead He today would not have been Lord, but vanquished. Lord' is Jesus' title obtained in victory. Jesus is Lord of that day He rose from the dead on; that day became "the Lord's Day", kuriakeh, by virtue of Christ's attaiment, on it. As Karl Barth put it, "What makes of this day this particular, meaningful day, is that which happened on it, and to it". Where Karl Barth said this about Sunday, I believe the Bible says it about "the Seventh Day Sabbath Day of the LORD your God".