Below is a list of possible preliminary knowledge for chemistry. It is well worth your time to take ten minutes every day reviewing one thing you've learnt in preliminary subjects. You're already doing so in maths you might as well extend it. Keep in mind that you should always stick to your study schedule and do the majority of this extra work when things are slowing down. Particularly during the holidays or the lead up to the holidays. If you don't do something now I guarantee you will regret it later.