You probably have quite a few commitments like school to take into account plus teachers might just carry on setting you homework.
So it kind of depends on how much time you have available ... if the exams are in November then you don't have a lot of weeks anyway.
Maybe start by looking at all the subjects and topics you have to revise and seeing how much there is.to learn. Then start scheduling the different topics into the time available.
TSR has a pretty good Study Planner that will divide up revision sessions into the time you have available - try it and let me know what you think.