Yeah it is, well, it depends on how much you have to revise. Take it like this, revise at least 3 hours EVERYDAY from NOW or from whenever, but ASAP. Make sure you revise according to the specifications and that your answers are full marks. Memorize any model answer essays if you can for those areas of the subjects where they ask essay styled questions? This will ensure you bank the top marks! But yeah, I'm in the same boat as you too, and I only started revising from YESTERDAY as it hit me how soon exams will approach if I don't take any action. You should take action now too! Stop worrying about it and do something about it. It is possible to achieve 3 As if you work soooo hard. It will be painful, but, "no pain, no gain"...