I just want you to see there that God has been working this thing out—thinking about it, thinking about His purpose—before time began! Time began when God created the heavens and the earth, by which we keep time. And, maybe, in one sense we would say that time did not begin until God created Adam. Then time became important. (Time does not mean the same thing to God.) But God has been thinking about the purpose that He is working out in our lives since before time began.
Everything "in one." One Body, one Kingdom, one Family, and one Church. That sets the stage for the rest of the book. Unity—we do not have it on earth. Mankind has never been "one" in the way that God wants man to be one. And so His purpose, which began before time.
That is what He is working toward, making us all one in Christ and that we could all be glorified in Him, as part of Him.