He waited until 11.35pm on January 1 to put in his appearance after alerting his mother Siobhan (29) at 2am that day to his intention to arrive a few days earlier than expected.
Mrs O'Malley, who lives with husband Christopher (28) on a dairy farm just north of Oamaru, said her first-born's birth date would be easy to remember.
While it might be a difficult time to organise parties when he was a "wee kid", having January 1 for a birthday when he was older would be "awesome", she said.
She understood he was the first baby born in Otago in 2012.
Yesterday young Finnian, who weighed 3.81kg, was tired after his birth at Oamaru Hospital's maternity centre, but Mrs O'Malley said she was not letting that lull her into a false sense of security about his possible future behaviour.
In Southland, Temple Aerepo (18), originally from the Cook Islands, gave birth to the province's first baby for 2012 at 4.23am on January 1 at Southland Hospital. He weighed in at 2.98kg.
Resting at home yesterday with her parents in Invercargill, Miss Aerepo said the baby's first name, Phizz, had been chosen because it meant first.
His other names are Bobby Johan Utia.
Since Miss Aerepo's due date was December 27, she agreed there had also been a possibility her son might arrive on Christmas Day.
