Cecil Patrick Kennedy, now 50 and living in Doonside, appeared in Sydney Downing Centre District Court on Friday charged with manslaughter over the death of 21-month-old Jordan Thompson in March, 2005.

Mr Kennedy pleaded not guilty in Newcastle District Court in August, but due to the length of the trial - a circumstantial prosecution case that is estimated to run for between four and six weeks - the proceedings were moved to Sydney.

On Friday, a frustrated Acting Judge Graeme Henson lamented the fact that, due to witness and lawyer unavailability, Mr Kennedy's trial could not start until mid-2023.

Ultimately, the trial was set down for June 26, 2023.

Mr Kennedy began a relationship with Jordan's mother, Bernice Swales, in November 2004, a coronial inquest into the boy's death previously heard.

It was the afternoon of March 19, 2005, when Ms Swales went to run some errands and left her son in the care of Mr Kennedy. When she returned home, Jordan was unresponsive.

She rushed him across the road to Singleton Base Hospital, but he could not be resuscitated.

Police were told Jordan had been found face down in the bathtub, but an autopsy later revealed high levels of a prescription medication used to treat depression in his system.

Homicide Squad detectives established Strike Force Kyeama to investigate the circumstances surrounding Jordan's death and coronial inquests were held in 2008 and 2015.

Ultimately, in 2018, the coronial inquest into Jordan's death concluded with Deputy State Coroner Elaine Truscott finding "Jordan died as a consequence of Amitriptyline toxicity having been deliberately administered anti-depressant medication containing Amitriptyline by a known person".

Following further extensive investigations, and the announcement of a $100,000 reward for information, Strike Force Kyeama detectives arrested Mr Kennedy at his Sydney home last year.