Only a couple of months left until exams!

Depends on what subjects you're doing and how many exams you have. I don't think you need to revise like a nutter; many, if not most people commence serious revision around March.

No stop imm st il in denial ffs

Don't go overboard with revision atm.
Just keep it consistent throughout the year up till exams.

Ideally, when should all of one's notes be completed by?

Revise!

Sciences and I'm aiming for high A's.

Hi,
I have only made notes on some topics in the syllabus and am consolidating my understanding on these topics. But I feel as though I won't make sufficient progress with notes etc, unless I start revising like a nutter.
Do you guys think I should sacrifice a significant proportion of my "free time" from this point onwards to study, given the considerable lack of time left to achieve the very top grades, high A's?
Or is there still time to comfortably coast through the remaining months?

At what grade are your sciences at this moment?

Mostly low A's.

You'll be fine. As I said, most people start revising around March-April. It's definitely possible to get high A's without starting revision as early as late January. For now, just concentrate in class and keep-up with the homework.

I would strongly advise you to start revising from now, at very low consistent rate, say 3 hours per week on top of your current work.

Revising from this point onwards would suffice, for high A's or would it be an unlikely feat?