i'll be honest with you, I got grades ranging from 4-9 in my mock exams over Year 10 and 11 and I didn't start really revising regularly until January 2020 or like 2-3 days before a mock exam
However, I'm a person that's "naturally smart" (always been in either 1st or 2nd set for all my subjects) so revising at that time might not work for everyone. When I say I'm "naturally smart" please don't think I just walked into a mock exam and got like a 7 though; I didn't. I mean that all through Year 10 and parts of 11 I was getting grade 8s on class assesments for Maths but grade 5s in the mock exams because I couldn't apply what I knew to the exams.
When I actually practiced past papers for maths I went up 2 grades in six weeks. The same is true for English, the first mock exam I did I in Year 10 I got a 4, I had to reevaluate my exam technique and the last exam I did in February I got a 9.
what I advise you to do is to DO YOUR WORK and PAY ATTENTION in every subject. Actually listen in class (it helped that my friends weren't in most of my lessons, i'm a chatterbox) and don't be afraid to ask your teacher for help, that's what they're there for. I advise you to make notes where you feel necessary, I only made notes for Bio, Chem, Physics, and English Lit as there's so much to know and just did past papers for subjects like Business and Maths and didn't make notes on them. I didn't even do anything for Drama or Spanish lol, I just walked into mocks. If you want a good grade in the sciences start making DETAILED notes EARLY (i started in Year 10, December and didn't even finish them for every topic)
At the end of the day, the most important thing is paying attention in lessons so that you don't leave the room not understanding something, because you'll have to address in the future. When it comes to revising for mocks you want to be confident in most areas so that you don't spend all your time trying to understand things you don't know; revising should be about practicing the things you already know to ensure you can never get it wrong. If you keep leaving the room not understanding things, you won't be able to revise.
I'm not saying to be a nerd and do every piece of homework (I rushed most of mine at break time loool or just made up a stupid lie) but just ensure that you understand things, so that when it comes to revising your not learning stuff, you're just refreshing your memory. If you come out of every lesson not understanding things, THAT is when you will be panicking when you're sitting in an exam and you don't understand half of the things on the paper. I know, I've done it myself.