I am by no means a historian or an expert on Australia. I don't know when or where Dows settled there. I did find this information which clarifies discovery dates for Australia.
Early European exploration of Australia began in 1606, when the Spanish navigator Luis Vaez de Torres sailed through the Torres Strait, now named after him, which separates Australia and Papua New Guinea. Before that, seagoing Macassan traders, originating from what is now Indonesia, would visit the north of Australia to trade with the Aborigines and harvest sea cucumber.
A couple of months after the Vaez de Torres voyage, Dutch explorers began to chart the new continent. First was Willem Janszoon, who sailed into the Gulf of Carpentaria, and then 17 years later, Jan Carstensz mapped and named the main features of the western coast. By that time, other Dutch navigators had reached parts of the northern and western coasts of Australia. Most importantly, Dirck Hartog examined the west coast near what is now known as Shark Bay, and Abel Tasman charted roughly the coast from Cape York to the Ashburton. The Dutch called the continent New Holland.
The first English explorer was an adventurer named William Dampier, who landed near King Sound, on the northwest coast in 1688. Dampier was followed by Captain James Cook in 1770. After circumnavigating New Zealand, Cook headed west to Australia. Sighting land near Cape Everard, in the southeast corner of Australia, he turned north charting the coastline as he went. After nine days he landed at an inlet that he named Botany Bay after the rich variety of plant life he found. The area is now part of the bustling modern city of Sydney.