I don't see the point in studying for VCE subjects this early.
Make sure that your taking it a step at a time, and that you really nail down Year 9/10 Math before even thinking about VCE math or you will be really struggling.
IF you are super motivated and smart, nothing is stopping you from going ahead and learning the material. But to be honest, it won't give you that much of an advantage.
The VCE course is designed to be finished in one year. So if you keep up to date, and don't slack off(maybe a few classes ahead) you'll be fine in Year 12.
But I guess it depends on the individual.
I've heard of people finishing the course before they entered Year 12 and started practise exams very early, and achieved a very good score.
I've heard of people did the same thing as aforementioned but got complacent and did very little until exam time, and then realised that they forgot heaps of things.
And then there are people who cover the course at the same pace as school, revise and start practise exams around late Term 3 to Start of T3 holidays.
100% of your English score directly contributes to your ATAR, so I think get into the habit of reading regularly. Novels, newspapers, anything really.... It will certainly pay off in the long run.
There's certainly no rush to think about VCE. Remember not to get too caught up on it. Enjoy highschool! Year 9/10 is the time where I recall having fun and not really bothering about schoolwork. (LOL, I was a bit too relaxed)
One thing I do advise is to make sure that you have a good work ethic now. (Don't leave things till last minute, hand all your homework in time etc..) as its a habit that will follow you til Year 12 and beyond...