Check it in the Manual List CSV.
The "created_at" in the Manual List CSV is the date and time when the manual was created as a draft.
If the creation date should be the date when the manual was first published, refer to "first_published_at".
* Exporting the Manual List CSV is only available to Administrators with appropriate permissions for the export scope.
Related: What does each item mean when exporting the manual list as a CSV?
Note that the creation date cannot be confirmed on the manual view screen.
When performing a PDF Export, "Updated (last updated date and time)" and "Exported (exported date and time)" are displayed.