They don’t mean revise from the beginning, they mean from like December/January (depending if you sit AS exams).
Psychologically, it is better to review things, so if you go over your notes and supplement them, after you’ve grasped concepts in lessons, then you would just have to review it in an exam, because learning and revising/reviewing isn’t the same thing. So ‘NO’ you shouldn’t making notes and learning them before an exam, however different things work for different people. Study effectively and not for a long time, studying for 5 hours straight is useless if barely any knowledge/understanding is attained.