When is the earliest day I can submit FAFSA?

I will be graduating high school in May 2021 and starting college in August 2021, so my first year of college will be the 2021/2022 academic year.

I will be applying to college during the fall of my senior year, which is the 2020/2021 academic school year.

Am I supposed to submit the 2020/2021 FAFSA or the 2021/2022 FAFSA?

I know that the 2020/2021 FAFSA submission window opened on October 1st, 2019. So, if I am submitting the 2021/2022 FAFSA, should I expect the window to open on October 1st, 2020?

File the 21/22 after 10/1/20

Or on 10/1/2020.