We did this last year. We're in Vic so it might differ a little....

So we bought the second house as our Primary Place of Residence, we were selling our house at the time but weren't sure how long it would take. Stamp duty was maybe $800 less for PPR as opposed to buying it as in investment . We had every intention to move in within a 12 month period (which we did) but rented it out in the mean time until our house sold (things for us were quite tight financially having both). You will have to declare your earnings from the rent but from what I know that should be all that you need to do. Definitely speak with your Conveyancer as they will be able to give you a definitive answer. All the best!