The short answer to this question is: a minimum of six months. But that answer requires a little more explanation. In order to start the divorce process in San Diego County or elsewhere in California, you must file a petition for dissolution of your marriage with the court, and then serve it on your spouse. The six month waiting period runs from the date the petition is served on your spouse, not the date the petition was filed.
Because divorce is a life-changing decision, this six month period gives you the opportunity to be sure that you really do want the divorce you've petitioned for. If you and your spouse agree on the terms of the divorce, you can use this time to reach a settlement agreement to submit to the court. The Judgment can be approved by the courtbefore the end of the six month waiting period and returned to the parties but the Judgment will indicate the date that the parties are officially "single" which is the end of the six month period. All orders in the Judgment are effective upon the parties signing the agreement and become orders of the court once the court approves the Judgment, even if that is before the six month period. If you do not reach an agreement or otherwise resolve the issues until after the six months, the date the court approves the Judgment is also the date that the parties are returned to the status of "single" persons.
There are different options for divorce in California, depending on your circumstances. The process is the same in San Diego County and all other California counties.
The California divorce or dissolution process proceeds by one person filing the initial divorce Petition. It does not matter which spouse (or domestic partner) files the initial Petition in terms of any legal advantage. Once it is filed, it is served to the other spouse along with the other required court documents. That person then has 30 days to respond to it. In California, you may have a contested divorce or an uncontested divorce.
You or your spouse may ask the court to enter temporary orders regarding things like child support and custody. You and your spouse will have the opportunity to conduct "discovery," which means to exchange information and documents that pertain to your divorce. Both spouses must complete financial disclosure forms prior to a judgment being entered by the court.
You, your spouse and your attorneys then discuss settlement. If you reach an agreement, then one of the attorneys will draft a detailed Marital Settlement Agreement. If you can't agree on all the terms of your divorce, there will be a mandatory settlement conference wherein all parties attempt to resolve the issues with the assistance of a pro tem judge. If that attempt fails, then the court will set a trial on the contested issues. Based on the settlement agreement or trial outcome, one of the attorneys will prepare a Judgment of Dissolution of marriage—your final divorce judgment. The judge signs the final Judgment, it is filed with the court, and notice is sent to all parties, which concludes the divorce process.