we went to Melbourne with DD (drive down) when she was 5 months old ... earlier than that would have been better as at 5 months she got very tired of the car seat very quickly and being rear facing it was just plain frustrating for her. She is now 10 months and is a bit easier to manage in the car but again gets bored very very quickly with the car seat and any toys to occupy her ... i honestly think the younger the better, esp in rear facing capsules ....