I'd go ahead and postpone the first two Godfathers (three is a backburner project), if that's your plan. They are fantastic movies, but you'll enjoy them later.
But you won't be able to put off Citizen Kane (or the first Fantasia, for that matter) long enough for your plan to work. No matter how long you wait, you will watch the whole thing, thinking, "What is this? This is nothing special. What is all the hype?" And then you will realize, bam. This was where all of those other movies came from. Nobody had ever told a film story the way that Welles and Toland did in this flick.
So go ahead and watch Citizen Kane now, and the first Fantasia, and you might as well throw The Battleship Potemkin and Intolerance onto that queue as well. If you're really committed to watching film history, get Birth of a Nation as well. Wow, that would be a weekend of early film propaganda at its finest.
If you REALLY want to make your head blow a gasket, here's a double feature for you - Triumph of the Will and Night and Fog.
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You can take the heart out of the hooker but you can't take the hooker out of the heart. -- Frankenhooker