When to take university classes in high school

Hello,
I am a grade 10 student currently living in Canada (I’m a U.S. citizen) and I want to attend University in the U.S. I attend a high school which is part of my local university so I can eventually take classes there. I am wondering whether I should take the university courses ( First year Calculus, English and Chemistry) in my junior year or in my senior? What looks better when applying for colleges? Thanks in advance.

Whenever you’re ready to. Earlier is probably better, as you will be able to take more of the upper level courses that colleges want.

If your current teachers think you can handle it, I would suggest English and either calc or chem junior year, and 2 more senior year (or 3 if you got A’s in both classes junior year).

Earlier is better as long as you can handle it. If you’re looking at top universities, it’s pretty important to throw the hardest schedule you can together and try as hard as you can to get As. Also, junior year grades will show up for universities.