if you're a single parent and receiving parenting payment single (at a guess based on your sig) you will automatically get the payments sometime late july or august. you don't need to do anything.

if your son was born in the current financial year, you wont get the full amount as you'll only get paid the supplement for the days you've had him

there is another thread in the Centrelink section titled something like "$600 per child payment" - its long but has all the info in there (sorry - too tired to go into all the details again - have put really detailed answers in that one though!)