In my opinion, organise your notes around 2 months before your exam, so in March. Make sure you have everything like past papers etc. Then start reading over your notes but only for like 20/30 mins a day. You don't want to do intense revision otherwise you'll burn yourself out. Around 4 weeks before your exam, start your revision. Make sure you understand your content. 2 weeks before the exam just do past papers.
But, it all depends on how you revise. Some can revise over a short period before the exam, while others may need more time.