For in him were all things created, in the heavens and upon the earth, things visible and things invisible, whether thrones or dominions or principalities or powers; all things have been created through him, and unto him; and he is before all things, and in him all things consist (Colossians 1:16-17).
Based upon what the holy text says, the creative act of Day 4 was the positioning of our solar system by Divine fiat in such a manner as to provide the environment for humanity.
It certainly did not require any twenty-four hours for God to say, “Let there be light”, and our understanding that God’s creation was by fiat, that He spoke the worlds into existence, and that all things appeared instantly upon the Divine word, forbid any notion that Almighty God required a time budget in any of His creative acts.