Well if you think the light on Day 1 must have been energy, that might explain why you think Morning and Night could only have been accomplished by having a Sun on Day 1 instead of Day 4.
But I think the more likely explanation is that initial light and/or energy allowed the first morning and night without the Sun.
You do understand that day and night are caused by the rotation of the Earth on its access with the Sun shining on half of it at a time, don't you?
You can rationalize all you want or claim faith over what the Bible says, but the fact is you can't have day and night without the Sun being present. The ancients would not have known this little fact, but that is no reason for you not to apprehend it.