Cal, that's a NIce bunch 'o knives there!
I believe the earliest jigging was the pick bone jigging, which is a kind of rough haphazard jigging, like the bone was picked at. The jigging on the knife I posted came somewhat later, as did the peachseed. For example, the one I posted is in the 1926 catalog, and Cal's big jack with the uber threaded bolsters shows up in the 1930 supplement. Dating anything pre-1926 is rather difficult since I don't know of anyone with an earlier catalog other that the old hardware store catalogs that may contain some Schrades. It seems that back in the early Schrade days a catalog wasn't deemed necessary since the majority of sales were done by salesmen who carried a knife roll with the actual knives in it. A picture didn't compare to handling the real thing.
Same goes for the switch to a straight line tang stamp, another Schrade mystery which might never be solved. I'll bet a lot of that old paperwork was still around when old Louis S. sold to Albert Baer. If only AB had not been so practical and kept the stuff for history's sake instead of tossing it. I think if it'd been up to Henry he would have saved it.
Speaking of Louis Schrade, Dave Swinden tells a story of how Louis was a stickler for inventory. If a run of 100 knives were to be made, 105 sets of parrts would be allowed for it, and every part, including screwups, had to accompany that run right to the end. He would toss a nickel on the factory floor and wait nearby till someone picked it up. He'd then dash over and ask "Why'd you pick that nickel up?" to which the person would reply " 'Cause it's worth five cents." "Well then why didn't you pick the blade up that was next to it? That's worth a nickel too!!"