Fall is the ideal time to seed a lawn. Prepare the seedbed according to the advice of a California Certified Nursery Professional before sowing the seed.
Water regularly until the grass blades become "bushy" and about three inches tall.
Four weeks or so after planting, you should be able to mow your new lawn. Allow soil to become firm and fairly dry before mowing in order to avoid damaging the new lawn with the mower wheels.