I believe that it is six months, got my permit for CDL and schedule my tests for 3 weeks later. The only hard part was the pretrip walk around. Good luck.
If you are talking about the DOT Commercial Drivers License, that permit usually is 2 years, with reduced 1 year/6 months/3 months versions for various medical issues.
In Arizona in '95 the CDL permit was for 6 months. Permit for regular non-commercial driver license was also 6 months in AZ for as long as I can remember. I've not heard of a non-commercial permit in CA lasting 2 years.