Hey I thought the world when first created was without day and night?
Okay so you have now defined a day in terms of an evening and a morning. How long is an evening and how long is a morning? Did a evening and morning take exactly the same amount of time 20 million years ago as it does today? From where are you measuring this day? On Earth or at the Center of creation or outside of time? Ever hear of Einstein and relativity? Is God's time the same as ours? Some theologians and physicists believe that everything that was ever created or will be created already exists and the reason that God knows the future is because God is outside of time and space.