When we have a choice between using our time for our studies or for spiritual things, which should we choose?

Sri Chinmoy: It is up to the individual soul. Some people do not want to study. I have searched their souls, and the souls do not want it. To some I have said, You have to study. Their souls want it. In your case, you need to devote your time and attention to spirituality. Spirituality must come first. You must have time for meditation, for selfless service.
For outer information you have lots of time, but for the inner life you have no time. But I wish to say that the spiritual life can easily be practised along with your outer life. Each day you can give two hours for meditation and one hour for selfless service. Everybody can give this much time. Some people will read all sorts of undivine things when their school work is over. They spend time on films, TV, comics and rubbish from the outer world instead of doing spiritual things.