You will have a limited amount of time to complete the project. This includes time in class and time outside of class at home and at school.
You also need to consider other commitments such as work and other school subjects and when there are periods that you might not be able to work on the project.
Break your project down into smaller more manageable chunks to make it easier to monitor your progress. It is easier to track I have made my player character move rather than a larger less well defined task like build a prototype player.
Always factor in contingency time to your project in case (when) something happens.