Service
At least 90 days of active duty, wartime or peacetime, with training time excluded. National Guard members and reservists who were ordered to federal active duty qualify on the same basis.
Discharge
A discharge under honorable conditions. If your character of service is anything other than that, the eligibility question gets specific, and it is worth asking before you plan a purchase around it.
No CalVet loan already
CalVet lends to a veteran who does not currently have a CalVet loan. A loan you have already paid off is a different question from one that is still open, so tell us which it is.
Residency, which is not a requirement
There is no California residency requirement for CalVet. A veteran who enlisted in another state can apply. The home itself does have to be in California, and you have to live in it.