@MayoMay for weather climate here, expect a colder weather if you're coming now up to end of october especially eastern states like sydney or melbourne. December is the start of summer season.
Sa timing naman on finding a job it depends on your target industry. Mostly, it would take months to settle and find a job of your choice lalo na if kasama mo family mo i.e. finding a house to rent, arranging job applications, car, medicare and centrelink, having children enroll etc.
I would say, there is no definite time to come in as long as you come in early, the better of an earlier chances to settle in. Mahirap din kasi ngayon makahanap ng job. All the best!