Jack, I think the shipment date to E.F. Warner is probably correct, as it mentions delivery of K-38 K4639 in the same shipment. The first commercially released K-38s with K plus four digit serial numbers were being released in February through April of 1948. The N-frames with N71xxx serial numbers were also appropriate for that time.
I think that S&W was designing the postwar K-22, K-32 and K-38 Masterpieces at the same time, but released the designs to manufacturing for commercial distribution on a staggered schedule. There were undoubtedly preview and salesman samples available from early on, and when K2244 showed up a few years ago, I think its early appearance was treated as a corporate favor to a major industry publisher. As you note, the K-32s were not available to the public at large until early 1949. In the spirit or refinement rather than argument, I would point out that there were a few K56xxx K-32s released in 1949, but the majority of K-32 serial numbers that year were K6xxxx guns.
I have a ghost memory of a few K-32s (10? a dozen?) being released for use in a national competition in December 1948. Maybe someone whose neurons are better connected than mine can flesh this thought out or correct it.