splistitem – Date of when a Field was populated

Is it possible to get the date of when a choice field was populated? I’m asking because we have a SharePoint list which is automatically populated by an automation and the entries are later reviewed by one of our team members. Whoever is reviewing the entry add his name to the entry through a choice field, and I’d like to get the date when the ‘Reviewed By’ field is populated. I thought about using a calculated column but I’m not sure what formula would get the results I’m looking for.