It's simply a rather problematic term and will always be subject to interpretation. It's not that difficult to determine when an actual war between two nations begins because it requires military action/aggression or atleast a public statement of such intentions. In contrast, a "Cold War" holds a contradiction. It's a war without explicit military aggressions, atleast none who target your "opponent". The term "Cold War" is basically a term which attempts to describe a period in history during which two "superpowers" went to great lengths to expand their own power and influence at the cost of the other while trying to avoid a full-blown military conflict - partially inspired by previous traumas and the perception of mutual assured destruction. So it's very difficult to determine when this strife started and when it ended simply because it depends on your interpretation/definition of the term "Cold War" and because the battle for supremacy between "superpowers" is hardly unique to this specific period in time.

That being said, I think the 1947-1991 dating is as good as any. Some say that this power struggle continued even after the fall of the SU and some say that it started before 1947. While those are all valid arguments, they are mostly born from problematic nature of the term "Cold War" and a concensus will always be subject to criticism. That's why I prefer the 1947-1991 dating, it uses important and invasive political events and public actions to determine the timeline of the "Cold War", which makes a lot of sense given that it's a war largely fought within the political sphere.