The year 4004 BC is widely accepted as the year of creation though different scholars give different dates. The actual date can never be known with any certainty, but for purposes of creating an Old Testament timeline we need a starting point and I have chosen 4004. For this timeline, I have relied on others for some dates and some I have worked out for myself. A number of dates, notably the dates of various psalms, are nothing more than a guess.
The date of 4004 BC is determined by starting with a point in history where the date on our modern calendar is already known and working backwards. The fall of Jerusalem to Babylon in 586 is generally used as a starting point. From there, we count backwards using the length of the reigns of the kings and the ages of the patriarchs when their children were born. This leads us to a date around 4004.
For these dates I have leaned heavily on the work of John C. Whitcomb, Joseph W. Schmidt, Edwin R. Thiele, nabataea.net, preceptaustin.org, and a few sites that seem to have been taken down or relocated since I consulted them.