When were our souls created? There is nothing in Genesis that tells us the when. But we do know they existed as it is the 'soul' which means breath of life, that God breathed into the Adam's nostrils that made him living.
Paul says some were predestined before the foundation of this earth age. Ephesians 1:4, one of many places Paul tells us there was an age before this flesh age. An age where the dinos ran free and flesh man were NOT hunted down and consumed by dinos.
There is nothing in the Bible to suggest a gap in Genesis 1, it is something people put there to try and explain evolution and creation and dinosaurs because they chose to believe men instead of God