The answer is they were probably aware of German Panzer tactics before the war, however Guderian shouldn’t be given too much credit for making them. Germany wasn’t really allowed to have tanks due to the Treaty Of Versailles, but they go around it through loop holes and having tank testing facilities in different countries or in hiding. The Russians maybe saw the most of German tank tactics as the Germans had a training facility set up in Russia in the 30s but they probably weren’t aware of any new updates. If any of these countries were aware of these tactics before the war, they did not apply them to their armored divisions. As each power already had their own doctrine and were set that theirs would come out on top.

Guderian was not that influential for tank warfare compared to the others that are barely mention. Men like Seeckt who started the idea of a combined arms warfare with tanks post WW1. Seeckt was the one who looked at how and why the Allies won and thought that tanks would be a big factor. And General Lutz who Guderian was under during the mid to late 30s. Lutz is responsible for making the Panzer arm to be on the same level as the regular army. He would make the Panzerwaffe what it was during the 1939-41 campaigns. Guderian would be one of the few Panzer generals to actually apply these tactics in battle.

Comparing what Seeckt and Lutz did for the Panzerwaffe, Guderian was the test pilot. While yes they updated the tactics even more and had battle experience to help refine them, Guderian should not be given too much credit. The reason he has so much hype as “father of Blitzkrieg” is because he wrote his legacy post-war and elevated his status above Lutz and Seeckt.

Source:

Habeck, Mary R. Storm of Steel the Development of Armor Doctrine in Germany and the Soviet Union, 1919-1939. Cornell Univ. Press, 2014.