Pregnant & moving to Oz - healthcare help!

Hi there, my sister is moving to Queensland with her Aussie hubby around June/July this year. She has just found out she is pregnant with twins and so needs to make sure she is there for her 20 week scan. Problem for her is that she has been advised not to fly until after her 12 week scan in the UK!

She's lived in oz in the past and had medicare but she wants to know how long it would take to arrange and get into the 'system'. Its vital that she has the 20 week scan at the right time in case she needs tests or further monitoring.

does anyone have any information that may help? does she need to arrive much earlier to arrange healthcare and book the scan?

PS - i'm posting on her behalf as she's not yet fully registered with PIO.