hi! i personally only started ‘proper’ revision in April, but I was doing some semi-regular reviews of content (particularly Y12 content) all through Y13!
I personally did these reviews through my decision to completely rewrite all of my Y12 notes to make them more concise and prioritise what I really needed to know (as I had a bad habit of just writing down everything from the textbook, which you don’t always need!). I also created revision materials for any new Y13 content at periodic intervals. So for example we’d have the lesson on a topic and I’d make some notes in that class, then around a week later I’d go through and make notes on any textbook/revision guide material on that topic, then a while after that (honestly anywhere from 2-4 weeks afterwards) and ‘clean up’ my notes to make them more concise! Then even further after that, I’d make flashcards or some other types of revision material so I could constantly be refreshing my memory on a topic!
Honestly lots of Y12 topics are the ‘simpler’ ones in your subject (ofc this is subjective, but there’s a reason teachers tend to teach them first, and reasons they’re included in AS Levels as opposed to other topics!) so I found I needed to review them less than some of my more complex Y13 topics.
Tldr; at this stage in the year I wouldn’t be worried about cracking down to revise constantly, review your Y12 content periodically and keep up with creating all your revision materials, but don’t stress so much that you forget about your new content!! You have another 7 months at least until your exams, it’ll fly by but let yourself breathe for now.