The 1952 K was pretty late-to-market. The first Ford Mustang was labeled as a 1964-1/2, and the K probably should have been called a 1952-1/2. But exactly when did it start?
We only have a few dates to work with. The K was announced at the November 18-21, 1951 Dealer's Convention in Milwaukee, as reported in the January 1952 Enthusiast. Four Ks were shown at the conference: two were up on the stage, "resplendant [sic] in white and chrome", a dark-colored bike, and a racer.
The next mention of the K's comes in the May 1952 Enthusiast, where there are three dates: March 15, when Texas dealers received their first K demonstrators; March 29/30 when 5 Ks were entered in the Shreveport, LA Pirate Treasure Run; April 6, when a St Louis, MO dealer won the St Louis Easter Egg Hunt. Also, there is an article by a dealer who took his K to Greenhorn Mountain, near Bakersfield, CA (no date given). There's a nice 2-page ad in that issue - you can see it down on the bottom of the Literature page - which may signal the start of public availability.
So it looks like 1952's weren't shipping, at least in any quantities, until around March 1, 1952. As The French Owl pointed out, the December 1, 1951 date I used in the Shipping Date Guess-O-Meter is not realistic. I revised the 1952 calculations to start on March 1.
Do you have any better information on the start of 1952 production?