If you have found an old real estate poster, letter or other document that has a date such as “Saturday 23 March” but doesn’t mention the year, you can use https://www.timeanddate.com. Copy and paste the link into your browser.
This website will display the calendar for any year you need.
As an example, refer to the old real estate poster above – Saturday 23 March. Select “Calendar” from https://www.timeanddate.com. In the next screen, select a date, which might correlate with Saturday 23 March in the approximate year that the land might have been auctioned. It shows that 1878 is a possibility. Other years in that period when 23 March fell on a Saturday are 1872 and 1861. The next step is to find advertisements for the land auction in the newspapers of the day. Knowing the year helps refine your search on Trove (https://trove.nla.gov.au/newspaper/).
The calendars in the timeanddate website also give you the days when Easter fell in each year, and the day on which Christmas and other public holidays occurred.