Creation occurred in two phases of three days each, which were sealed by a third phase of the great rest.
The two initial phases are easily seen in a simple reading of Genesis one: God first creates the environment, and then the object to fill it: day one is the separation of light from darkness, day four corresponds with sun, moon and stars. Day two is the separation of waters above from waters below, day five corresponds with birds and sea creatures. Day three is the separation of the waters from the dry land, day six corresponds with land animals. On day seven, God rests.
Some interesting things to note:
First, God is three, and His creation mirrors Him; He creates out of Himself, as nothing else Is: you are in Him, or you quite simply are not at all. There is only one real option, as there is only One Real God, and He claims existence itself as His attribute, as His very Name.
Secondly, the foundational creation consists of division: light from darkness, waters from waters, waters from land. When there is division, there is usually a creation, the most obvious being the Red Sea and the creation of God's cevenental nation. When there is a merging, there is destruction, and to stick with the water analogies, the flood seems an obvious choice.
And, the final thing that I will note on this topic will actually introduce my next one: the primal theophany.
The recently late Meredith Kline has an excellent book called Images of the Spirit, in which he notes the (three) accompaniments of the great appearances of God, the great theophanies. They are as follows: Light or day; darkness, and the qol or sound (often a voice). All three of these are to be found in the first three verses of Scripture.