Jandals is in Qld, our prep system is different to kinder - the rules are frustrating at times. I am not sure about starting part way through the year - I know if you moved you certainly would be allowed to do this, but not sure whether you can if you are already living in the intake area. I also am not sure about the benefit of starting part way through the year, as she will have missed all of that the other children have learned. She may also find it difficult socially to start part way through a year.
Is she attending kindy or childcare with others her own age? Do her teachers there share your concerns about not being ready?