Well, if making it better is the criteria, then 1948 is better. However, that being the year, it means that Vito returns to the mall in February 1946, remains in his sickbed 10 months of 1946, all of 1947, and several months of 1948 before rising to resume command of the family. That's a long time.
As TB does, I believe that Sonny was murdered in the spring or early summer of 1946 and the Dons' meeting took place that summer.
It would have been summer 1946 at the very earliest as Puzo hinself writes in the novel that Sonny went on the offensive during spring and sumner.
