Mr Justice Griffith Williams, who presided over the trial at Mold Crown Court, told the court he wanted "time to reflect" before passing sentence, though he warned Smith her life sentence was fixed by law.
During the three-week trial, the jury heard that Smith had a "propensity" to threaten people by saying she would burn their houses down "with their children inside" and made a string of threats to Ms Shiers in the weeks before the fire.
They were told Smith had been increasingly angry with Ms Shiers, accusing her of being a noisy and untidy neighbour, and that she complained to others about Ms Shiers leaving the pushchair in the hallway.
Today Melanie Smith will be told the minimum term of her life sentence.
More top news
Traders in Monmouthshire say they could lose out when many roads are closed for the first Velothon Wales event next month.
A cat rescue charity in Ebbw Vale is worried it won't be able to find homes for its 70 cats.
A teenager is calling on the Welsh Government to lower the age of cervical screening for women - after she was diagnosed with cancer.