I trawled the first three years of the Sydney Gazette (1803-1806) to see what I could find in the way of advertisements from women. The population of the town, less than 20 years after the start of British settlement, was just a few thousand, so there probably wasn’t much need or incentive to pay for ads. The Gazette came out once a week, and for was often only of two pages, so not a lot of room for ads either. (And as you can see the scans are low quality so searching the OCR text for keywords is… interesting.) But I found a handful easily enough.