What is the test for a plaintiff to successfully plead a motion to dismiss an action that was brought prematurely?

The matter is controlled by the rule set forth by this court in County of San Mateo v. Bartole (1960) 184 Cal.App.2d 422, at page 430, 7 Cal.Rptr. 569, at page 574, as follows: 'It had long been established in this state that the defense that an action is prematurely brought is a matter or abatement which must be pleaded in proper time or it is waived. Moreover, after this [238 Cal.App.2d 655] defect has ceased to exist, it cannot be interposed for the first time.'