Hielly, if you are really tossing up between whether or not to actually write notes (which is a lot of the responses seem to be addressing) then in my opinion you should. Especially for biology, there is so much information to cover. From my experiences with biology last year a few things to keep an eye on:
- write notes with one eye on the study design, print out the key knowledge and keep it with you because the books go off track
- separate the basic biology theory and the examples: I say you should know examples because it can help you write your answers and additionally they have sometimes used examples that common popular textbooks feature in the exams.
- Don't let them go on for too long.
- Incorporate all the different sources you have into one collection, I didn't do this and I feel it made the whole revision process more sapping
And there is nothing wrong with starting notes now, just the part that concerns me is if you don't understand a concept. This is just me personally but I don't think writing notes on a concept you don't understand is helpful at all. It's better to understand it. That's not to deter you from writing notes, but rather to say that you should be trying first and foremost to understand the concepts before you write any notes.