If you believe you will have a refund or no balance due an extension is not required.
Resolution is to send the CA return with the copy of the W7 and a statement indicating you have applied for the ITIN. An extension is not necessary and then you know the return was filed on time. When CA requests information you can respond at that time with the number or an explanation you are still waiting on the ITIN. There is nothing to indicate you should wait to file.
For more information you can use this link about CA extensions: CA
Automatic Extension