Is there an established theory (rather than the one I've just made up) that assumes God's ability to manipulate time?
It seems to me that if God had a viewpoint outside the laws of physics, he could cause the big bang and accelerate time (or go to sleep), place Earth at the point in time and space he chose, sleep some more, then place Adam and Eve at a suitable point in time.
Essentially, God's days are as long or short as he chooses them to be, depending on how much he has to do (like Santa on Christmas eve).
Think of a cooking program where they are showing you how to make a roast. You are told that the preparation time is 10 minutes. Time spend marinating or cooking is less relevant and makes very poor television.