To determine the age of the earth from the Biblical narrative is impossible. God did not include the date of creation because time as perceived by us is not a priority for God. We should not think of God’s creative acts contained in the morning and evening days of the creation narrative as a function of linear time. As human beings we perceive our existence as a passage of a linear period of time. We are born into time, we live for a period of time, and we pass out of time. Not so God. God exist in eternity. There have been many attempts to imagine and describe the nature of an eternal existence free from linear time. It will not be attempted here.
It will be enough for us to understand that God fills all time at the same time and His acts of creation would not be perceived by Him as stretched out over a particular period of time. God sees your birth, your passing, the lamb slain before the foundation of the world and every other event simultaneously.
God would perceive events in time as we would look at a map of the world. God sees the beginning and end of roads of history, the intersection of events, the boarders of change as well as every short side street. God’s activities in all of the aspects of creation would exist for Him simultaneously. It is important to our limited perception how long something may take. For God how much time something may take to come into existence is not relevant to His act of creation. This is why there is no reference to a specific period of time anywhere in the creation narrative. If we are to begin to comprehend God’s act of creation we must not limit Him to human abilities and understandings. For God all the events of His creations are just borders of change on a map perceived all at once and the years of any one of our lives are contained in a very short driveway.