The doctrine of creatio originans refers to God’s original conservation of creation–a sustaining causal relationship. This doctrine typically entails an A theory of time.
A theory of time (dynamic): The ultimate reality of time is tensed (God is in time)
B theory of time (static): The ultimate reality of time is atemporal (God is outside of time)
The doctrine of creation implies an A theory of time (dynamic, tensed). If one adopts B theory of time, then things do not literally come into existence. The whole four-dimensional spacetime manifold exists coeternally with God.
Creatio continuans entails a B theory (a continual creation). According to B theory, all events are equally real. Yesterday is just as real as tomorrow and exist in the same moment. If creatio orignans fails, can B theory make more sense of conservation?
Can God act tenselessly on e to sustain it from t1 to t2 [a time interval]
No. What if e exists only at t? Or what if e is the whole four-dimensional spacetime block? On a B theory of time, no such lapse occurs, and so conservation is unnecessary, indeed, excluded.
This is “one of the most neglected, but also one of the most important questions in the dialogue between theology and science,” which is the relation between the concept of eternity and the spatiotemporal structure of the universe.  B theory’s supremacy is due largely in part by ignoring realities of the Hawking-Penrose singularity theorem in 1968, a singularity as a boundary to spacetime (this has forced A theory and creatio originansback into the spotlight). With creatio ex nihilo and a singularity (confirmed by mathematics, philosophy, and science) an eternal universe is impossible leaving us with a tensed beginning to the universe.
As physicists John Barrow and Frank Tipler observe, “At this singularity, space and time came into existence; literally nothing existed before the singularity, so, if the universe originated at such a singularity, we would truly have a creation ex nihilo.”  Even if God remains intrinsically changeless in creating the world, He nonetheless undergoes an extrinsic, or relational, change, which, if He is not already temporal prior to the moment of creation, draws Him into being time at the very moment in virtue of His real relation to the temporal, changing universe. Even if God is timeless without creation, His free decision to create a temporal world constitutes also a free decision on His part to enter into time and to experience the reality of tense and temporal becoming. 
Like the incarnation, the creation of the world is an act of condescension on God’s part for the sake of His creatures…His timeless, free decision to create a temporal world with a beginning is a decision on God’s part to abandon timelessness and to take on a temporal mode of existence…He stopped to take on a mode of existence inessential to His being or happiness in order that we might have being and find supreme happiness in Him. His taking a human nature into intimate union with Himself in the incarnation of the Logos…was thus not what the Danish philosopher Kierkegaard regarded as “the Absurd,” union of eternity with time, for God was already temporal at the time of the incarnation and had been since the inception of creation… As a result of God’s creation of and entry into time, He is now with us literally moment by moment as we live and breathe, sharing our every second. He is and will be always with us. He remembers all that has transpired, knows all that is happening, and foreknows all that is to come, not only in our individual lives but [also] through the entire universe…He is, as Isaac Newton said, the Lord God of dominion throughout His universe. Well did Jude exclaim, “To the only God our Savior through Jesus Christ our Lord, be glory, majesty, dominion, and authority, before all time, and now and forever! Amen!” 
 Wolfhart Pannenberg, “Theological Questions to Scientists,” in The Sciences and Theology in the Twentieth Century, ed. A.D. Peacocke, Oxford International Symposia (Stocksfield, England: Oriel Press, 1981), 12.
 John D. Barrow and Frank J. Tipler, The Anthropic Cosmological Principle (Oxford: Clarendon, 1986), 442.
 William Lane Craig, Philosophical Foundations for a Christian Worldview (Downers Grove, IL: InterVarsity, 2003), 559.
 ________, Time and Eternity: Exploring God’s Relationship to Time (Wheaton, IL: Crossway, 2001), 241.