California permits are only required for jobs that film in California. There is no need to obtain this permit until your agent advises you to do so.
CLICK HERE for information on obtaining a performer permit in the state of California.
Additionally with the California permit, you will need to open up a Coogan Account which is a blocked trust account. CLICK HERE to to learn more on how to open this type of bank account. It must be a CA Coogan, not one from a different state.