In late 45 or early46 the best I can tell with possibly a few stragglers along the way. I had a real nice stag with "3 1/2" blade grind with two pins that was post war so either late 45 into early 46. I don't think it took long to drop the second pin. The third and fourth photos are of a 1-8" from around the same period in a left over WWII sheath either prior to the switch to plastic snaps or was in the bin. In any case, it has one pin. I currently have a 2-8" with stag and single pin from the original owner that got it in 1946