I'm about to try chocolate transfers for the first time, mostly just to practice. If they turn out well, is there some way I could store them and use them on a cake in late November? Or would it just be better to make them again when the time comes?

They should be fine for a couple of months--just make sure you keep them in a cool, dry place--not in the refrigerator. I can't think of any reason why the transfers would be any less stable than the chocolate you started with.