you do get a choice. you cannot be forced to take paid parental leave over the baby bonus. from the family assist site:

If you think you may be eligible for Parental Leave Pay, you can use the Online Estimator from 1 October 2010 to help you decide if you want to receive Parental Leave Pay or the Baby Bonus. The Online Estimator will ask you to answer questions about your circumstances and will provide you with a comparison between Parental Leave Pay and the Baby Bonus.
from my understanding - if you're already at the cusp of not receiving ftb, you're probably better off with the PPL than the baby bonus. over a period of 18 weeks, you get just over 10k, as opposed to 5000 or just over for baby bonus - which is paid fortnightly for 26 weeks. PPL is taxable though, so you have to take into account how much tax you're going to have to pay on it given you will have worked for a fair portion of the year and this will add to it.

something you will need to consider is whether the income is more pressing for you on a fn by fn basis before returning to work. there are provisions to quarantine and pay the max amount of ftbb from when your mat leave runs out until you return to work. given i'm assuming you're due in march-ish, if you took your fully paid mat leave from work, it would run out fairly early in the new financial year. if you delayed baby bonus until then, you would likely be eligible for baby bonus plus ftbb of around 130-140 a fn. if you receive PPL, no matter WHAT your income is for the financial year, you will lose eligibility for ftbb for the period you are receiving PPL

there is a lot to consider when working out which option to take, and i guess, as hard as it it to wait, it might be better to wait til October 1 when the online estimator is updated so that you can see what you're entitled to and work it out for your family. i do agree that it seems to be, in your circs (with no ftb entitlement anyway) better to get PPL and get it after you have been paid your mat leave. i would check with your employer if you're eligible to take your other paid leave while taking time off post-birth though - a lot of them will let you take it before you start your mat leave, but require you to go back to work before being eligible for other leave