What is the effect of counsel advising defendant not to testify at trial?

Notably, whatever the reasons for trial counsel advising defendant not to testify, defendant at the time found them sufficiently sound to indicate twice on the record that he accepted his counsel's advice and would not testify. In similar circumstances, where a defendant claimed he was deprived of his right to testify due to counsel's advice but first raised this with the court only after his conviction as a ground for a new trial, the court rejected the claim outright as untimely, explaining: "Defendant did not apprise the court he desired to testify at any time during the trial proceeding when the right could have been accorded him, instead he waited until an adverse verdict was rendered against him before advising the court he had really wanted to take the stand after all, then demanded a new trialanother chance before a new juryon the ground his counsel had 'deprived' him of his right. The obvious unreasonableness of such an approach doubtless led to the established rule that a defendant who desires to take the stand contrary to the advice of his counsel must make proper and timely demand." (People v. Guillen (1974) 37 Cal.App.3d 976, 984-985.)