http://apps.dmv.ca.gov/pubs/hdbk/ca_dl.htm
New California Residents
When you become a California resident and you want to drive in California, you must apply for a California driver license within 10 days. Residency is established in a variety of ways, including the following:
Being registered to vote in California elections.
Paying resident tuition at a California college or university.
Filing for a home owner's property tax exemption.
Receiving any other privilege or benefit not ordinarily extended to nonresidents.