It's hard to defend a firm timeline due to inconsistencies within the canon.
For instance, Crazy Joe uses the Senate Chairman's statement "in the year 1950 you devised the murder of the heads of the so-called five families in New York" to support 1955. But how would he possibly know when the killings were "devised?" And why would he bring that up rather than the actual dates of the killings?
Yes W, you make a point that I have made in previous posts. It's the film's timeline v. that of the novel and within the novel there are timeline related discrepancies.
However, I posted elsewhere what you did: why would the Senator refer to Michael's devising a murder plot , but completely ignore and never mention the murders themselves? It makes no sense: "Mr. Corleone, we know you arranged the murder of these guys, but what we want to know about is the devising of it. To tell you the truth, that was brilliant. Can you walk us through it?".
In additon, I find it, at the very least, incongruous that Vito and Michael would let nearly ten years go by before they carried out their revenge murder plot. Think about it: Michael and/or Vito could die; Michael and or Vito could come under singular law enforcement scrutiny; Michael and/or Vito could be imprisoned; Michael and or Vito could be murdered. Need I go on?
