How much should I study for Grade 6 theory to get good marks in it If I do not know anything at all?
have not done any music in VCE, but I have done AMEB music theory.
I did up to grade 5 AMEB with a teacher. Personally I didn't find music theory too hard (found it easier than practical) but you still have to put in the effort (even though it's not that much). It does involve quite a bit of memorization, like memorizing terms (which a lot you should know cos you play music anyway), I remember back in my day we had to memorize short songs but I believe they changed the syllabus? not too sure...also I think in grades 4/5 they introduce like melody-writing and stuff, but there is a set of rules for that...there's also cadences/chords too but yeah, there are sort of "rules" for that but playing piano, you might know a thing or two about them? (e.g. perfect cadence V-I, plagal IV-I + imperfect and all that etc)...anyway I'm going on a ramble now soz
(right now I've forgotten about 90% of my theory though)
I did start grade 6 but I stopped cos it was pretty hard as my teacher stopped teaching. If you do not know anything at all about theory, idk how long it'd take to get up to grade 6, because it does get complex later on even though grades 1/2 are pretty easy, but seeing as you have musical experience a lot of it should be straightforward in the lower grades
good luck