Kids are schooling. So I tried tkts to SYD during holidays - but it appears that I need to book 9 months ahead!

Could you give me some tips:
- when might be a time that is easier to book (summer, winter ...)
- what airlines and/or port?
- if you book well ahead, can I still fully recover points and possible fees if u had to cancel?

I am open to workarounds, say fly from LAX, Toronto ...possibly Van Cover ...

Plan is to use Advantage points.