Latest date to file a PERM for Green Card

My wife has just 1.5 years on her H1b after which her H1B will be over.

What is the latest date till which she can file the GC process?

Is it true that with PERM you can extend H1 by 1 year and with I140 by 3?

If your PERM or I-140 is pending for 3 years, then one can extend 1 year at a time.

If your I-140 has been approved, but dates are not current, then one can extend 3 years at a time.