The new $2 billion Royal Adelaide Hospital will finally open in September, about 18 months behind its original schedule.
Premier Jay Weatherill and Health Minister Jack Snelling say the new hospital's emergency department will start taking patients from September 5.
Ambulances will begin transporting about 300 patients from the existing hospital to the new facility over three days from September 4.
Mr Weatherill says the move is one of the most significant events in the state's history.
But opposition health spokesman Stephen Wade said the government can't be trusted and expects the opening date to be pushed back further.
Mr Snelling says he's "very confident" the government can stick to the timetable, but admits it could be changed if needed.
"This is something that only happens once every 200 years and it's important that we get it right," Mr Snelling told reporters in Adelaide on Monday.
In the six weeks prior to the shift roughly 300 patients will have been transported from the old RAH to other hospitals in Adelaide.
Some services that do not require an overnight stay, like radiation oncology and various outpatient clinics, will be offered at the new RAH from mid-August.
The Australian Nursing and Midwifery Foundation SA said it's significant that 2000 nursing staff affected by the move had "a solid date to work towards", while the Australian Medical Association SA said doctors and nurses needed to be involved in the planning process.
Mr Wade said the new opening date for the hospital, which was originally meant to open early in 2016, was "just not credible".
"Jack Snelling has never met a predicted opening date and this is the one he is least likely to meet," Mr Wade said in a statement.
Last year the SA government launched legal action against the hospital's building consortium after delays in the facility's technical completion.
Two deaths on the hospital's building site, in November 2014 and February 2016, have also added to the controversy.
