The NW Monsoon starts November/December so that will give you favourable winds. However, the
South Pacific cyclone season also starts in December and Timor Sea, Arafura Sea, Torres Strait and the NE coast of
Queensland (Coral Sea) are all in the cyclone zone. The
passage can be done, but you do need to keep and eye on the
weather and consider where you can go for shelter if an early season cyclone does develop.
Generally leave Borneo to port and travel to the north of the 8* islands, leaving Timor to starboard. Are you planning to
cruise with stops in
Indonesia or going straight through?