Write concise notes and do flash cards now and do them nicely and keep them till year 11, it will save a lot of time
I’m in year 11 now and most of my revision time is taken up this, but I guess in a way it’s good as it helps me remember and understand the stuff
Don’t do too much now as you will probably burn out, but if you understand the topics already and keep going over them/remember them that would be very useful later on, but you could eventually get really tired of it and by year 11 you’ll be tired and won’t try hard
Which subjects are you doing? and how many?
Also lots of people in my school started revising after christmas and some in march and they still all got good results but everyone at my school is excessively smart and the school is really pushy so I don’t know how that would go for other people