In first year of A-levels, I made notes as I went along. I tried to keep up with the class sessions so after the lesson I’d go and look through my textbooks (click here to see which ones I used for Biology, for Chemistry I used the same ones in my Chemistry specification) and add to my class notes. This sounds like a simple task but was actually quite time-consuming so kept me occupied throughout the year. I’d re-read these notes throughout the year and try to memorise them. I only started practising questions once we had finished covering all the content (which was around Easter).
In my second year of A-levels, I decided to actively pause my A-level note-taking schedule a little so I could focus more heavily on my medical school application and preparing for interviews, so I didn’t really keep up with enhancing my notes after lessons. After my interviews were over (mid-February) I then began going back over the lessons from the beginning of the year and reading through the textbooks. I fully put my head down so I did mange to get through all the lessons quite quickly.
It was around mid-March that I decided I needed to condense the content because it was too much to learn in the format it was currently in and that’s when I wrote up my Biology and Chemistry summary notes in which I stripped down the content to all the things that you actually need to know. I did a few summary sheets a day and memorised them on the same day. And after that I went through past papers.
Although I went through this whole process with revising for A-levels, to give an overall answer to your question, I’d say the time that my real revision began was after Christmas in first year and in March in second year.