Currently, there is no way to track when someone first submitted a replenishment. The Date Request field should signify a static "submitted on" date, but if you edit it later at any point, it then updates the Date Request date. The original submitted on date is really useful to make sure replenishments were submitted on time. If they update it, a last updated column would be useful as well to have a change log, but really the original created date is most crucial. Please consider making the Date Request field static.