Fanfiction advice and help

Well, I'm kinda stuck on and idea for a fanfic, but the problem is it's historical so I'm not quiet sure where to start.
I want to do a completely accurate fic on America to study for my AP American History class, but I'm not sure if I should have America come into existance when people first crossed the Bering Strait, when the Spanish colonized the very souther portions of North America or when the British finally came in like 1606 (ish). Or when the Vikings went to Newfoundland in about 1000.
Also do you think "America" represents the 13 colonies, if so then would there be a different character of the Native Americans.
Just wondering what you guys think.

Not American here. I think the comic implies America comes into existance when Spain reaches Florida, circa 1500. Why do I say this? America is a baby when the first nordic settlement occurs, which makes sense historically, if he appeared not that long ago, and it also makes sense that he has that age. Second, because America is a child of modern Europe, I believe he totally represents the European settlements and colonies and not the original natives. Himaruya even had a Native American tan in older strips, fighting alongside France agaisnt England and America! America represents the Europeans that took control of the New World, not the original people that have nothing in common with the USA and weren't even united (which makes it impossible that there be a common representative for all the very different native tribes)

That's along the line of what I was thinking too, thanks!