What Divvy said. It's generally suggested to start living on one income whilst you can and save the other, so you get used to it. It may take 28 days, it may take longer, depending on what else Centrelink have on at the time.

Also, dont assume you'll finish 2 weeks before your EDD. I thought I'd finish about 36weeks with DS1, but the SPD was so bad by 25 weeks I was on crutches and finished work at 32 weeks.

Treat PPL like a bonus, which it is, and learn to live on one wage, starting now.