I'm assuming other people have said so already, but there's really no need to start this early! It's only February! You probably still have coursework to do, so focus on that if you do. If you don't, then just focus on keeping up with the work you've got at the moment, rather than actively revising. If I remember right, A2 exams are after May half term, which gives you a whole term between now and then. Starting revision over Easter is probably about right. Unless you've done literally no work since September, then you really don't need to start now. It won't help. Of course it depends on the subjects you're doing, and on the individual as everyone has different techniques for learning, but I don't think I started any revision before the easter holidays, unless I had mocks beforehand.