The hearing in the High Court at Christchurch, before Auckland-based Justice Judith Potter and a jury, had been scheduled to begin yesterday.
But disputes over some aspects of the case meant a two-day delay to allow time for legal argument.
Weatherston (33) is charged with murdering 22-year-old Sophie Kate Elliott, who died at her Ravensbourne home on January 9 last year.
She had been stabbed or cut more than 200 times.
At the time of her death, Miss Elliott had been about to leave for Wellington and a job with the Treasury.
Evidence at the preliminary hearing in May last year was that Weatherston arrived at the Elliott family home on January 9 and that, after being allowed in, attacked and killed Miss Elliott in her bedroom.
Much of the evidence at depositions was suppressed, including details of the wounds inflicted on Miss Elliott.
When it became apparent yesterday more time was needed for legal submissions, Justice Potter excused potential jurors until 10am tomorrow.
