best time would be after april when the north west monsoon has finished as after torres srt's you will have predominatly westerly head
winds,with the possability of tropical storms between darwin and bali.
the east coast
is still generally out of the south east and you have a reasonable chance of a cyclone,but with shallow draft
and good weather
info refuge can be sought fairly easily.
i would expect the trip to take any thing from 3-6 weeks being very weather
dependent in those months.
lots of oppertunities to get fuel
as far as cairns,then ti,gove ,darwin are the only realistic stops ,untill indonesia
,then a cruising permit
might be needed for stops before bali.