WHEN? Is the main question!
When is by far one of the biggest questions! A great flood whether local or global would have left a serious amount of damage in antiquity.
A few other questions to consider as we walk down this path are…
1) Timelines of some major civilizations are well documented and as such which of any were missed or destroyed by such a catastrophe?
2) Also, what was the main purpose of the deluge?
3) How long was the great deluge?
4) How many survived?