My Standard Catalog of Smith & Wesson is the latest 4th edition, which was published in 11/2016. In the book, the revolver serial number info date back to 2015. I suppose the "DMD" prefix must be later than 2015.
Somebody else may have better, more recent, s/n info. The original box's label would be the best source, I suspect.
Based on some pics online of guns with labeled cases and close serials, DMD would seem to be late 2019 or early 2020. Anyone who can narrow that down would be appreciated.