Start revising from the start, take all your mock seriously and dont cheat in them. I planned to finsih first half of all modules by christmas and then the 2nd half by March then the weeks afterwards was just redoing past papers again and again and again. (I did most past papers 4 times).
How i revise is.
Look at the specification sheet. There will be bullet points. Write a paragraph or more about each using information from the exam board accredited textbook. It takes around an hour a topic. (should only be from half an A4 side to 2-3 A4 sides) So takes you 10 days to finsih the first half of the years content (the first unit). Do that for all three subjects and keep the notes very tidy, leave some sapce for edits.
That way you know for a fact youve covered everything in the subject so now its just learning how to use it in exams.
All three subjects in this way takes 15-30 days (I did two topics a day, 1 topic for 2 subjects). per unit.
Now that you have your notes. Read them (takes 30 mins to an hour). Make sure you understand everything. Only remember things in lists if stated so in the spec sheet (eg the only tests you need to remember for chemistry and biology are in the spec, dont remember additional ones or alternative methods if its not on the spec, takes too much room in your head). Now do all the exam papers for that spec (and the previous spec if there arent more than 4-5 papers). and afer you do every single one, mark them extrememly harshly, IF the wording is slightly wrong etc then mark it wrong. No one ccares about your practice paper scores it only matters to you. Now every single thing you get wrong, be it a list of events or marks for a generic photosynthesis advantages question, list everything at the front of the exampaper, (the page where you write your name). Read the front page of every paper before starrting a new paper so you have your notes in your head and the mistakes youve made in the past (and things youve forggotten to mention or maybe didnt spot).
Do all the papers for each subject (takes a day per subject if you dont do anything else at all)
After doing the above do exactly the same for unit 2's then just keep doing exam papers again and again and again. Theres only a few ways examiners can word a question so you just need to learn what to look out for. Always aim for 100% on the exam. If you dont understand why you have tos ay something or why the answer is as it is then ask a teacher. You must undertsand why you have written your answer for every question thoroughly.
Also after youve done the papers all twice then write down the common questions and lists of bullet points on flash cards and read them on the walk home or to college. You can also put all the raw memory stuff on those aswell earlier on the year (all the tests and flame colours etc and equations).
I probably did all the exam papers from my exam board 4 or 5 times. Biology had like 10 past papers for one unit too.
ps i wrote this in a rush so sorry for the bad grammar.
(i got A*A*A in bio chem phys).