New Holland Becomes Australia

From In For The Long Haul: First Fleet Voyage & Colonial Australia: The Convicts' Perspective, by Annegret Hall (ESH Publication, 2018), Kindle p. 415:

Increasingly, the continent of which New South Wales was part of became known as ‘Australia’ in official communications and documents. Captain Matthew Flinders was the first to adopt this name in the 1814 publication of his charts and journal of the exploratory voyage. The use of Australia for the colony rather than New South Wales first appeared in The Sydney Gazette in 1816. After that, the name ‘Australia’ was widely used. A year later, Governor Macquarie introduced it into his letters to the Colonial Office and on 21 Dec 1817, he recommended that henceforth the continent and colony be called ‘Australia’ rather than ‘New Holland’.

The first Australia Day celebration was held on 26 Jan 1818 to commemorate the 30th anniversary of the colony. The official celebration of this day paid tribute to Arthur Phillip ‘whose virtues and talents entitle him to the grateful remembrance of his Country, and to whose arduous exertions the present prosperous state of the Colony may chiefly be ascribed’. In recognition of the anniversary, a 30-gun salute was fired.