Kyle Maspero, 18, was referred for mental observation last year and was now number 23 on the waiting list, said prosecutor Susan Galloway.
When he appeared in court last month, he was 37 on the list.
Galloway asked Judge President John Hlophe to postpone the matter until March 27.
Maspero, dressed in a smart black suit, tie, and purple shirt, clasped his hands in front of him as Hlophe reminded him to abide by his bail conditions.
Last year, the court ruled that he be held at the hospital for 30 days after his lawyer William da Grass, said Maspero was having difficulty instructing him.
“There is a failure to recollect material aspects of the offence and this is because of a protracted and heavy use of narcotics,” he told the court at the time.
“This condition existed even at the time of the offence and we wish to prevent a situation where difficulties arise at a later stage.”
Da Grass said Maspero had been using tik (crystal methamphetamine) for an extended period. There was scientific evidence to suggest it caused biological and physiological changes to the brain.
“Colloquially, the brain has been damaged due to drug use. I think that’s the simplest way to put it,” Da Grass said.
At the time, Galloway withdrew the same charges of murder and defeating the ends of justice against 20-year-old co-accused Godfrey Scheepers.
Theron’s daughter Phoenix Racing Cloud, 19, entered into a plea bargain with the State last year.
She admitted helping her boyfriend Maspero strangle her 39-year-old mother with a rope in her home in Fish Hoek on March 7, 2013.
Scheepers allegedly helped the two move the body and rebury it in a shallow grave.