Hey Shep ... have been checking out Mercuryfor the last week, and even took some pics last night. It is
very low in the West, and gone by about 8pm (our time) if not earlier.
Have you got Stellarium? It is a great free program -you pop in Cairns in the location and it will show you what you can see.
Mercury is in Saggitarius but well and truly gone by ... after 8pm.
Mercury is the brightest object in the SW (where Sun sets at moment) from when its dark - have a look tomorrow night.