I'm not speaking for my self here but for other hard working friends I know.
It depends on what revision you find best for yourself, and how much online stuff is available for what you do.
One of the subjects I done was maths, which probably is the easiest to self-study using online resources - ExamSolutions website is enough to guarantee you at least a B, or even an A* if you work hard, in Maths.
I didn't do any of your subjects, but as a general advice, I would advise you to start revising since day 1 if you're aiming for top grades.
Literally, just do around 1 hour a day since day 1 up to your exams and you will be fine (maybe increase it to 2 hours when you get closer to exams).
It could be watching videos on your topics, making notes (or using textbooks and making notes), and
very importantly, doing a lot of past paper questions - and understanding a paper FULLY, before going onto the next one. Not just doing a paper, losing a lot of marks and hoping to do better in the next paper. Look at the mark schemes too and try to study the best ways to answer your questions. Make sure you look at your specification, so you know exactly everything you need to and don't need to know for your syllabus. Also, if there is a topic or subject or area you are not as good at as the other one, focus on that one slightly more.
If you do it consistently since day 1, you will be fine.
Best of luck!