Connolly left her house saying, "I'll be back".
He returned a short time later, when the woman was in the shower, and went into her bedroom.
He poured a purple liquid from a sports drink bottle onto her carpet and set light to it. Flames immediately engulfed the room.
The woman and three other female occupants of the house escaped and firefighters put out the blaze before it could cause structural damage to the house.
However, the carpet was burnt and the bedroom walls were charred. Furniture, clothing and possessions in the room were destroyed.
When police found Connolly the following day, they discovered in his car 150 grams of dried cannabis head in five snap lock bags, a set of electronic scales, 19 cannabis plants in two boxes, and a lighting rig.
After a jury trial, Connolly was found guilty of arson, burglary and possessing cannabis for sale.
He appealed against his 64-month prison sentence to the Court of Appeal.
He argued that the sentencing judge had adopted a "manifestly excessive" starting point for determining his sentence, and had misapplied the totality principle which looks at the offending overall when imposing multiple sentences of imprisonment.
Connolly also argued that the judge failed to give him credit for a cultural report which had described a "very sad upbringing" blighted by alcohol and violence in his home, leaving him "a child living in constant fear".
Connolly also said the judge had failed to give him a discount for alcohol and drug issues, or to give him any credit for time spent on electronically monitored bail.
The Appeal Court panel of Justices Goddard, Ellis and Dunningham rejected all of Connolly's arguments apart from the one concerning his time on electronically monitored bail.
The judges said that the cultural report which detailed his childhood was "on its face, inconsistent" with Connolly's parents now being his chief support people.
A probation officer's pre-sentence report said that Connolly's parents had told the report-writer that they had always supported their son and would continue to do so.
However, the Appeal Court justices found that there was a sentencing error in that seven and a half months Connolly spent on electronically monitored bail was not taken into account by the sentencing judge.
They said a discount of three or four months should have been applied to his jail term.
The judges quashed the five-year, four-month jail term and imposed a sentence of five years instead.