Legal Question in Civil Litigation in California

You have ten calendar days unless the court ordered otherwise. The ten days will typically begin on the effective date of service of the notice of ruling, which means you'll get five extra days if the notice is served by mail within California, two extra days if it is served by fax or overnight carrier, etc. But if you waived notice at the hearing, then the ten days began immediately.

Mr. Hoffman nailed it dead on. You have 10 calendar days (which means Sundays, Saturdays and holidays are included) to file the amended complaint, unless the court ordered a different time. The 10 days runs from service of the notice of ruling, unless the parties waived notice in open court and the waiver was noted in the court minutes.