The question still remains valid as the proposed solution of adding The Creation Log Column does not have anything to do with the fixed timestamp of the form submission.
The Creation Log datatype is dynamic and is intended for tracking the latest change on the board, not recording constant timestamps.
Welcome to the community, and thank you for your request!
As per @JCorrell reply, the creation log column will (/should) remain fixed at the time the form is submitted/item is created. Is this column not behaving as it should on your end? Let us know incase we need support to investigate!