Total hours revision for GCSE Watch
Hell, write down short summaries of what you did in class each day or at least note the topics. That way you won't have to do so many notes later and can simply start scanning through them for revision purposes.
E.g 3 weeks before my first exam I did about 5 hours of revision everyday.
In the March/April period I focused by revision on subjects that I need help in, (English language and lit) and subjects that I am going to do in Six form (Maths and Physics).
(total hours about 200)