Dear Laura,

I have a little advice first of all for you, then we can speak about your father.

The first thing you have to understand is that you are still young and your parents are still responsible for you. At your age God wants you to obey your parents. So even though you want to do something else that is good, and even if you feel that God is calling you to do it he still wants you to show your love for him by your obedience to them. So you show Jesus you love him by honoring your parents which, at your age, means obeying them.

Now, about your father. What I said just now doesn't mean that you shouldn't try to explain what you want to do, why you want it, and why you think it is what Christ is asking of you - without making a pest of yourself, of course. He may be a little wary of this being only a passing whim of yours, something you will change your mind about and regret a few months from now, so you will have to look at your own motivations and reasons to see if he is right. Maybe he doesn't know what the precandidacy really is, so you should try to have someone else besides yourself explain it to him. Maybe he thinks that you are not ready for the commitment, then you will have to show him you are. Maybe there are responsibilities at home that you cannot leave right now, then you will have to accept reality.

As you can see, there are lots of "maybes". On top of this, a lot will depend on where your Dad is as regards his faith, and where your mother stands on the whole matter.

Practically, every time you receive Jesus in Communion tell him that all you want to do in life is please him and bring others to know and love him. Ask him if it is his will for you to be a precandidate to help you explain it well and to open your parents' hearts to the idea - it is a big sacrifice for them, perhaps even greater than for you.  And make sure to tell them simply and sincerely your reasons, and offer to have someone come to explain a little more to them about the program. 

God bless.