They'll be asking you about such things as your major, your work and your career. The culture can't wait for you to figure out your occupation. Let it wait. Work on figuring out your vocation. Just like your English teacher told you, check the roots.
Occupation comes from the Latin occupare , to take over or possess.
Vocation is from the Latin vocare , a call. In other words, occupation is something you choose. Vocation chooses you, by name. Occupation is what you take. Vocation is what you give.