One of rules to claim a primary home sale is "live 2 years out of the last 5 year". "When does the 5 year start when I sold a primary home 2 years ago?"

Count backward from the date of the closing.

Thank you.
Would you please confirm one more?

So, the 5 years doesn't get reset from the date of my first home sale date?

As an example, May, 2022: the first home sale.   Owned the second home from 2019 and lived 4 months in 2020, then living at the second home since July 2022.  Can I sell the second home in May 2024 and get the primary home sale tax benefit? or should I sell it after July, 2024?

You can only use the exclusion once every two years.

Yes, I understood "every 2 years"

Question is that
After 2 years, I have lived in the second house for 20 months, but lived in the second house for 4 months 4 years ago.  Can I get the tax benefit exact after 2 years (since I lived 20 months + 4 months 4 years ago)? or Can I only get the benefit after 2 years and 4 months (because the 5 years requirement reset on the date of the first home sale)?

I appreciate your time & help.

No, that is fine; the number of months do not have to be consecutive.

Thank you again, but....
I also understand "nonconsecutive" period.
One CPA told me that the 5 years reset after the first benefit (aka first home sale).  Since my 5 years term was reset on the date of the first home sale, the 4 months living at the second home 4 years ago is not part of the 5 years.

I even cannot find that "reset" rule any other place.  I asked the CPA to send me a reference of the "reset" rule but am not sure if he will response.