Just post WWII is my best guess. The Sta-Sharp mark was not used long after the war. As can be seen, the Sears mark was migrating from the pre-war Sta-Sharp/Kwik-Kut/Dunlap to Craftsman. Dual marked for a short span. Beautiful knife!
Oh... and Phil or another former Camillus employee or knowledgeable collector... please do correct me if I am wrong!