Labour Day has been an official Queensland public holiday, celebrated on the first Monday in May, since 1912 and before that as Eight Hours Day since 1901. Before its official recognition as a public holiday, parades and celebrations had taken place in Queensland since the 1860s. The first celebration took place in Brisbane on 16 March 1861 and was essentially a celebration by a small number of skilled building workers who had recently achieved an eight-hour working day. The date of the event was chosen to coincide with the anniversary of the first workers achieving the eight hour day in Queensland.
You can read more on the SLQ blog http://blogs.slq.qld.gov.au/jol/2016/05/02/labour-day-history-in-pictures/?fbclid=IwAR0sSy3zGSRPUJBAS7AKMJq5lvhydJYH5EhxVxSUbrGnaVqqdNI-Dk9bynE