You can check this in the Manual list CSV.
The "created_at" field in the Manual list CSV is the date and time the Manual was created as a Draft.
If you want to use the date and time the Manual was first Released as the creation date, please refer to "first_published_at".
※ Exporting the Manual list CSV is only possible for Administrators with permissions corresponding to the scope of the export.
Related: About each item in the data when you export the Manual list
https://help.teachme.jp/hc/en-us/articles/900005507846
Please note that you cannot check the creation date on the Manual viewing screen.
If you perform an Export PDF (Export), the "Updated (last updated date and time)" and "Output (date and time of output)" will be displayed.