Wycliffe Bible Commentary states that it is not correct to think of a day as a 24 hour period of time. It is the premise of the author that because the sun and moon are not created until later, that the measurement of time has not begun. He believes that a day is referring to a day of God and not to a day measured in hours and minutes.
Stephen Schrader in the KJV Commentary tells us that the word day has been used in three different ways in Genesis. In Genesis 1:5, 14, 16, and 18 it is used as a twelve hour period of light. The other two ways are a twenty-four hour period and in Genesis 2:4 the entire creative week. The phrase “And the evening and the morning were the first day” indicates to the author that the word used here is a twenty-four hour period of time.
Kurt Strassner in Opening Up Genesis ponders the questions “What is God like? Where did we come from? What are we here for?” He believes the answers come from the first two chapters of the Bible which span just seven twenty-four hour days. He solidifies his stance on the twenty-four hour days, by discussing evolution. One reason he gives for his stance against evolution is that the Bible gives us no reason to believe that the day in question is anything other than a twenty-four hour period. He notes that while it is true that Peter says in 2 Peter 3:8 that a “day is like a thousand years and a thousand years like one day,” Genesis 1 says over and over that “there was evening and morning,” which is indicative of one day as opposed to a millennium.
There really has been no question for me as to whether the day in Genesis refers to a 24 hour period of time or not. I agree with Strassner and Schrader that it does refer to a 24 hour period of time. I don’t think the Lord God needed an entire day to create all of creation. As far as the argument that we cannot call it a day because the sun, moon, and stars had not been created yet; if God calls it a day then who are we to argue. Ultimately it seems a bit ludicrous as well but if it took God six thousand years to make the earth and then He rested as an example to us, do we then rest for a thousand years?