Here is quick one liner hot to get a report on when Active Directory group has been created. This could be asked during audits so here is the PowerShell one liner:
Get-ADObject -Filter 'ObjectClass -eq "group"' -Properties whencreated | Select-Object name, whencreated | sort name | ft -AutoSize
This will provide you with nice report or list of all AD Groups and their date,time when they were created in Active Directory.
Enjoy!