FTB is an annual entitlement, broken down into fortnightly installments (if that's how you wish to have it paid) - you would, as advised, need to calculate what your annual income would be, and work out from there what your entitlement would be. it doesn't work on how much you get each fortnight. if you're entitled to a payment, you are entitled to that same payment EVERY fortnight. you can turn payments off and on, but it's a pain really.

parenting payment is very different to FTB and it works on the amount earned on a fortnight by fortnight basis. your combined income needs to be under 1500ish per fortnight (from memory) to qualify