Shanks’ bet: Accident or Intention?

One Piece Chapter One. Higuma kidnaps Luffy but Shanks comes to the rescue. After this incident another “incident” happens. A Lord of the Coast bites Shanks’ arm off. In Chapter 434, Shanks reveals to Whitebeard that losing his left arm was a wager. He sacrificed his arm to motivate Luffy to become a pirate. But my question is, did Eiichiro Oda plan for this to be a wager all along, or was it just a dramatic beat in the story? Well, to find out we have to think back to Chapter One. Shanks was not a Yonko. Shanks became a Yonko four years after Chapter One’s ending. In addition, Shanks scared the Lord of the Coast away, he didn’t use Conquerers Haki. At least is wasn’t called Haki. Conquerors Haki wasn’t introduced until Chapter 716. So what do I think? I think that Eiichiro Oda created that scene and didn’t think much of it but later used it as foreshadowing after the fact. I wouldn’t say it’s impossible that Eiichiro Oda knew it would play out like this all along. Wano was first mentioned in Chapter 450. The Wano arc started in Chapter 904, so Eiichiro Oda definitely does think ahead. But in this instance I’m not counting on it. What do you think?