HI!!
I'm going to Year 12 this year too, and ngl, I haven't done any 'learning ahead,' either (although I really promised myself I would).
Its great that you've finished your homework, as most teachers ensure they that prep work that will be the most beneficial to you to start with.
Just make sure that you have got a good rest and are ready to start school off the right foot. Its so important to make sure you get back to school energised! What Sine said is absolutely right, and so important to keep in mind. For me, to help with not learning content early, I'm planning to work ahead in Term 1, rather than the holidays. For me at least, I only have 3 SACs in Term 1, so I'm planning to go through extra content in this time.
Good luck! I'm sure you will be fine
Just work hard throughout the year.