Time leading up to the cross and time flowing from the cross.
Before salvation appeared and after salvation appeared.
A time of promise and a time of grace.
B.C./A.D.
Genesis 1:1 is a dispensation of time. Verse 2 was the end of that time. Verse 3 to the end of Chapter 2 is also a dispensation of time and describes a rejuvenation of this earth to be inhabitable for what Christ said to Nicodemus was required for any to 'see' the kingdom of God.
We are NOT told when our souls/spirit were created, but they have to preexist if we return to the Maker that sent us. Paul talks all about predestination and that is also a dispensation of when certain people were conceived and born in time appointed. Some people were predestined before the foundation of this age ... Ephesians 1:4 Paul certainly was predestined to be where he was when he was.
Jeremiah 1:4-5 Jeremiah was know before he was ever placed in his mother's womb and he was predestined to write and warn the House of Judah the king of Babylon was coming to take Judah captive, as well as look out for the safety of the King of Judah's daughters. These things are written as Paul says in ICorinthians 10:11 Now ALL these things happened unto them for ensamples: and they are written for our admonition, upon whom the ENDS of the world (age) are come.
If events like the Millenium, the Great White Throne Judgment or the creation of a New Heaven/New Earth do not mark different eras in time, I guess you could just as easily argue for two eras of time (different from yours): before Creation and after Creation -- B.C./A.C. :)