I'm currently in year 11 and finding it a breeze, it's one of my best subjects and I perform well without having to study a lot, it also helps that I find it enormously interesting. Which astounds me as from what I've seen, it's the highest scaling humanities subject rivaling the best scaling sciences, in theory, it should be a relatively difficult subject, so what I'm anxious about is that it'll just get dramatically harder next year with significantly harder concepts and more content to reflect its scaling and my grades in year 11 won't necessarily mean I'd do well next year.
Same position as you a year ago. It might be helpful to develop a regular routine for studying economics in Year 12, with more focus on essay plans etc. early on so it'll be less work for you by the trials.
Personally, my lack of study in Year 11 carried onto Year 12 so I would cram in the last 3 days in making essay plans, studying content and so on and even though my performance did not drop, I feel it would've been less intensive/exhaustive if done periodically.
Would highly suggest to study content from all the topics early on, especially if doing Globalisation on the first term, since you'll find the content in each topic is not distinct but rather overlaps heavily - You'll find it easier to integrate economic concepts, graphs and theory into essays etc.
Regardless, economics is a really fun subject as you might know but I'd suggest trying to do some "essays" early on to get the gist of HSC economics. I found in prelims the essays were not as prioritised as your knowledge but in HSC they're (imo) very important to master early on.