What are the requirements for filing a Petition for dissolution of marriage, a.k.a. "divorce?"

In California, there are two residency requirements that must be met before one may file a Petition for dissolution of marriage or "divorce." First, one of the parties must have been a resident of the state for at least six months;  and second, one of the parties must have been a resident of the county in which they are filing for at least three months immediately preceding the filing of the Petition for dissolution of marriage. If either one of the parties meets these requirements, then either party can file a Petition for dissolution.

What if you recently moved to California, or the county, and don't yet meet the requirements but still want to start the process? One could first file a Petition for Legal Separation and then once one met the residency requirements for a dissolution of marriage, one could then amend their Petition for Legal Separation to a Petition for Dissolution of Marriage. However, the new Amended Petition would have to again be served on the other party.