Revise regularly from after Christmas. GCSE's are essentially just a memory test so repetition is key! I find spider diagrams and using a whiteboard to write things out helps!
Just get down and diry with revistion and working in class. Put aside all the jokes and mucking around in class and focuse on learning. Its boring and hard at times, but after just one year, you've got the foundations for your life in place. Trust me, its worth it. Good luck for the exam season!
Don't start too early. I started arguably too early, ended up lacking motivation, and not using the notes I made That said, give yourself enough time. Both are equally dangerous.
Focus on heavy content subjects like your sciences Annotate all your poems and your texts for english so you dont waste time annotating when exam season comes closer. You should have mocks in couple of weeks/ months so revise for them. Print out past, mock, specimen papers for all of your subjects. (Ask your teachers if you cant access them) There is 7-8 months left till our first exams so there is plenty of time so you dont have to stress out yet. Starting early means you are more likely to get those high grades.
Try make sure you understand everything that is taught such that revision won't be too difficult.
Earliest you should start is January. If you are already confident with your subjects, then start sometime around March or April. It ultimately depends on how good you are and your aspired grades.
Revise at least a week before, definitely don't do what I did and start either the night before or the morning of the exam!! I still don't know how I did 'well', but don't leave it too late
I would say revise little and often througout the year (recap things from last year and stay on top of your notes etc) and then pick up the pace after Christmas. Stay organised the whole year too, so that you know which units you're doing when and that you'll cover everything, but leave free slots in your revision timetable i case you get any deadlines/extra work/just need a break so that you can be flexible without ruining your timetable! That way you'll hopefully reduce last minute panic and be really pleased with your results! Good luck
Revise what you DON'T KNOW. Don't revise the things you already know just to reinstate the fact you already know it !!! (Obviously, you can go through it but don't spend too long doing so because it's a lot of time wasting).
Also while revising turn off your phone/laptops/tv, such a distraction!