I have to disagree, there are references in Tress that only make sense if you have, at least, read era 1 of Mistborn.

Now I haven't read everything in the Cosmere yet, I'm about half way there, but I've read every book that anyone has ever recommended as a starting point, and as it stands, Mistborn is the best place to start if you're hesitant, and Elantris is the best starting point if you are committed.

That is mostly because Elantris, is one of Sanderson's weakest works, and could discourage some readers, if they come to the conclusion that it is how Sanderson will write all of his stories.

That being said, I would still rate Elantris as above average in quality compared to other books in the genre, and the ending provides the best introduction of Hoid without risking missed references.

Mistborn is a solid starting point, the only real downside is, the reader will have to be told to look for Hoid to have any chance of noticing him.

Tecnically you could start with Warbreaker with minimal negative impact, but I believe it is best enjoyed right after Stormlight 1, as it is referenced in Stormlight 2.

Speaking of Stormlight, if you really want to jump straight into the deep end, you can, but I'm getting a lot of enjoyment reading those books with the further context provided (so far) by Mistborn era 1 and Warbreaker.

And that covers every reasonable starting point.

His kids are born in the 1800s but they don't live in the 1800s for long.

Sure there's an argument to be made that a family living in a small western town for a few years and then disappearing could have significantly changed history through the butterfly effect, but it's not guaranteed.

It's not a theory, everything you said is established fact in the movies.

Unless you're suggesting that Doc knew everything even during the Twin Pines timeline, then you're talking nonsense.

The only glaring plothole in those movies is the fact that Marty's memories never get rewritten when his past is changed.