There are several types of family and civil restraining orders in California, including an emergency protective order and protective and prevention order.
F.C. 6240 et seq. allows the court to issue an emergency protective order, upon an ex parte showing that “a person is in immediate and present danger of domestic violence, based on the person’s allegation of a recent incident…” Here, since the threat occurred 10 months ago and was not acted upon, is likely is not immediate or recent enough for an emergency protective order.
However, F.C. 6320 et seq. allows courts to issue protective and prevention orders to enjoin “…attacking, striking, stalking, threatening…”. The court deciding on a protective order will need you to show that “substantial evidence,” exists to justify issuance of a domestic violence restraining order against your spouse. Here, despite the threat being made 10 months ago, one could argue that substantial evidence exists to enjoin your spouse from threatening you if the threat was grave enough, your spouse had a history violence and if there has been contact.
I would suggest you contract a California attorney for additional help.
In Tennessee, it is generally accepted that the threat be immediate. While a 10 month old threat may be relavent as background, something newer would generally be required.