Well, that's why I said at the outset that we can't rely on the films. In addition to the sloppy writing in the novel, we have the discontinuities between GF and II. I'm guessing that the reason FFC and Puzo set Anthony's party in late 1958 was so that they could create the magnificent Havana sequence, including Batista abdicating. So, they created the Michael/Kay "seven years ago" dialog to accommodate 1958. If they followed the novel's scenarios, it would have been "11 years ago," or "12 years ago."