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
Rain and drizzle will clear eastern counties this evening. Remaining mild with breaks in the cloud by dawn.
A leading vet charity warns that you could end up with a stressed, lonely or even aggressive pet if you don't care for it properly.
From pensioners to first-time buyers to public sector workers, a rundown of how today's Autumn Statement and Spending Review affect you.