I don't see how that would work. This development isn't just a plot thing, it's the start of his character arc. Having this be the first scene would be like if in soul, Joe Gardener dying was the very first scene, with us having no idea what his life was like before this point.
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Like, let's say the first scene is him "becoming the chosen one" via magic stuff. Then what? He gets saddled with a random girl who did conspiracy against the throne as her punishment, then he goes to tell his sister he's the chosen one and she's all excited that this happened and nearly in tears because she always had hope this would happen. Then he makes plans to go kill the dark lord, who we don't even know about at this point, as the mystery girl then says "actually no you're not the chosen one, I know how the chosen one works".
And then on the way he meets the real chosen one, and this is a big deal because he's an oil beast and that means something I guess. And the main character is incredibly angry to learn that someone else has the chosen one powers, and denies that the other guy could ever be the chosen one because it's supposed to be him. But of course he needs to keep him because he can't just fight the dark lord without the chosen one powers for some reason, but if he tells anyone about the other dude he'll be killed for existing for some other reason. Then decides he has to keep him a secret, meanwhile the actual for real chosen one is on the run from a massive coven of witches who are hunting him for some reason or other.
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Doesn't that sound so confusing? Like what is anything in this story right now, and why does this character do anything? We wouldn't know because he have no introduction to what his life is usually like or what the world is like or why this any character here feels the way they do about anything, and instead he's just thrust into the plot. It's like the lord of the rings but there isn't a shire.