I'm in year 11 and my exams are in 2-3 months time, and honestly start revising from the start of the year whenever you get chance! Start revising now and keep any notes or however you revise for later too. I only just started my serious revision and it was such a mistake because there is so much to remember in sciences alone. But it can be fun, don't think of it as a hassle! I bought a set of coloured biro pens and a sketchbook and I find it best to make mindmaps for each topic (as I'm a visual learner I can sort-of see where each fact goes in my mind in a test because of the colours). However I really don't find cue cards useful, but it's all personal preference! Good luck in your future mocks and exams! (Also don't stress if you get below a target or what you want, look where you made errors and remember that doing extra practise questions [or fake mocks which you can get on here and I would think your teachers would not mind marking] will help you with answering the questions how the exam board want you to!)