Shanghai 144 HR Visa Free Transit Application

I'm planning on visiting Shanghai for business purposes for 1/2 days next week before stopping over in Singapore, then flying back to Australia. Is there a rule saying you have to purchase/confirm tickets before a certain time i.e. 144 hrs before your arrival? I'm reading the shanghai immigration website and it does mention something along the lines of this, but looking at English sites, it does nothing mention anything about this. Can you please clarify?