A heavy downpour showered the North-West town of Ventersdorp on Monday morning ahead of the appearance of the pair accused of bludgeoning right-winger Eugene Terreblanche.
An application for a postponement by the defence would be made as it was not ready for trial, counsel Zola Majavu said.
Police vans lined the road outside the Ventersdorp Magistrate's Court by 7:30am as media began to arrive.
The National Prosecuting Authority said there would not be a separation of trial.
“For the proceedings they will appear together in the same court but in terms of the legislation they will be tried under different acts, one for the adult and one for the minor...There will be no separation of trial,” spokesman advocate Mthunzi Mhaga said.
The two had previously appeared separately.
Media houses wanting access to the trial had to apply as there was a shortage of space, he said.
Only 10 journalists would be allowed into the courtroom.
Some media groups had also applied for the case to be open.
Renovation had been carried out on the dilapidated court building since the last court appearance.
The repainted white and green building was now surrounded by a high grey picket fence.
Chris Mahlangu, 28, and his 15-year-old co-accused allegedly murdered the Afrikaner Weerstandsbeweging leader in April at his farmhouse.
Mahlangu was released in July on R5 000 bail but re-arrested in October after a Pretoria High Court judge said the magistrate in Ventersdorp had made “incomprehensive findings” in his granting of bail.
The judge found that Mahlangu was a flight risk.
At a previous appearance, the court heard that Terre'Blanche carried a panga with him everywhere he went and he frequently took off his underpants because of the heat.
Shortly after the murder there was speculation, fuelled by reports of Terre'Blanche being found dead with his pants down, and that he had attempted to sexually assault his killers.
It was revealed during the bail application that the trio had been consuming alcohol before the incident and were in a “jovial” mood.
The motive for the crime was believed to be over a wage dispute and missing cattle.
The court heard that Terre'Blanche had been struck with such force that his jaw was broken and a bone had pierced his tongue. - Sapa