Do not worry too much about what you will be learning and when, all flight training courses are structured to ensure a natural learning progression. It will be down to your ability how quickly you progress through any training that you do but you will go through the same steps that everyone else does.
I'd concentrate more on basic Maths and Physics than the intricate details of Radio Navigation as that will be much more worthwile if you do embark on the long and tortuous road to a career in Commercial Aviation..