I suggest that you login your wife and kid's info at EOI. The latest first entry time depends on the date of your body-checkup and the police clearance. For example, the body checkup date is on May 30 and the police clearance is on April 30, 2013. Then you and your family must take the first entry before April 30, 2014. But the trip can be a short one to active your visa. Then you have a 5-year time to decide when to land permanantly. Good luck.
The granted visa is effective for 5 years. You must have the first entry in the first year since your body-checkup or police clearance certificate date. The frist entry means go through the custom to activate your visa. You can fly back to China right away after the activation. After that, you can stay in China and go back to Australia any time before the visa expire date.