In June this year, Powell, who claimed he was paid $10,000 to kill Blackmoore, was sentenced at the High Court in Christchurch to life imprisonment with a minimum non-parole period of 10 years.
Rebecca Wright-Meldrum, 48, was also charged with murder, along with a 47-year-old man who has interim name suppression.
They have pleaded not guilty.
A three- to four-week trial was scheduled to begin at the High Court in Christchurch on February 15 next year.
However, at a pre-trial callover before Justice Rob Osborne this morning, it was revealed that the trial date will be delayed.
A new trial date is yet to be confirmed.