Whilst it's good to be eager for VCE, it's equally as important to keep things in perspective.
My coordinator at school keeps telling us that VCE is a marathon, not a race. Even though it's good to think ahead, you should not be wishing to skip so far ahead because you will probably eventually burn out.
My advice is to definitely do a 1/2 in year 10 and then do a 3/4 in year 11 (or even try and do two 3/4s in year 11 if your school allows it). Studying a subject a year early is invaluable experience and helps you to work out how to study best and can give you a good motivation boost into your final year.
In terms of this year for you in year 9, I would advise you to enjoy it. I miss the simplicity of the younger years at high school, and you probably don't think they're so significant now but they can be (and should be a lot of fun). As others mentioned, throw yourself into extra programs at school like debating, sport or music. Or maybe even volunteer outside of school, volunteering is a great way to give yourself some new found wisdom and perspective.
Like others, I barely understood how VCE worked in year 9. Just focus on creating yourself as a person instead of thinking about the years ahead of the VCE. Even though VCE is a lot of work, it is a very small part of our lives overall. And it shouldn't all be about studying either, hence why it's important to establish hobbies now to carry you through your later years when things get stressful.
Overall, just enjoy yourself. For me, year 9 onwards went incredibly quickly and I don't think I really appreciated it. And I now regret not just appreciating small things and meeting people and going places and well, just being a 15 year old.