John,
I hold my seed until late February or March before planting so they don't come up too early and get zapped. However, in your area of CA you might do better to start them now and let them grow all winter. That way they would be big enough next spring to make it through the rigors of your summer. You might try dividing your seed into batches and see what works best for you.
Even here I like to give the seedlings a little shade as the tiny seedlings are very vulnerable.
Of course after 6" of rain here in Salem, mine are pretty wet right now.
Kevin
