No matter what school district you move into, that school district must accept your children, once you prove you and they live within the district. You can do that by showing them your deed upon buying a home or your signed rental contract and your utility bill showing you are paying for the utilities at the address at which you live. The school must accept them if school is session and find them a seat in class. There is very little wait.
To find out which school district a property you are considering is in, go to USgeocoder.com and click on live demo. Put the street number and name in the left long box, and the 5 digit zip code in the small middle box. Then click free look up on the right. All information about which school district, which town or city, if not in a town or city, what county, and who the political representatives are for the property all will be available when you click the + signs. My wife's company owns and developed USgecoder.com, with me as the development manager of that web service. Please tell me how you like it.
Enjoy coming to California. I would very much like to help you find a home. You may call me at 408-639-0211 or email me at email@example.com.