___________________We know this took place because it is discussed by Vic (he talks to Vernon Peggles on the telephone) early on in episode 41-11-20 Rush Humiliated on Thanksgiving.
Though Vic and Sade lasted the duration of the hectic pre-war years and certainly spanned the time during the wars in Europe and the Pacific, the show has been noted for it's lack of war talk and for being nearly incommunicado about "patriotic" ventures such as the promotion of buying war bonds; this episode though helps prove otherwise.
[Note that even though war bonds is the subject here, this episode took place prior to 41-11-20 Rush Humiliated on Thanksgiving and certainly before the attack on Pearl Harbor.]
Although we don't know the exact date, it seems likely this episode would have aired in November of 1941. The title is one I have given the episode, purely for identification purposes only.