I would like to know, do you take piano lessons? Are you now taking organ lessons? What about theory?

If you are already taking piano lessons and have to pay for organ lessons, I would consider asking for help with these. They are expensive.

Depends on the understanding you enter with the music director, and on your keyboard skills/musicianship overall. It's hard to believe that my last parish growing up before I "went professional" with organ playing didn't even have an organ, so I *had* to get a paid (really low paid) organ gig on Sunday mornings within a few months of my beginning organ lessons, on the basis of my keyboard skills/musicianship from years of piano and my sight-reading ability, in order to play the organ for services regularly at all. I was a freshman in high school at that time.

By sophomore year in high school (a year into lessons) I was generating $100-125/wk in income from service playing, and by the end of my senior year in high school I was a parish music director making very good money.

Then I partly paid my way through college as paid organist in the college chapel, and on graduation became a parish music director, which is presently about half my income; this summer, I'm moving out of state to take on my first full-time church music job.

So I guess what I'm saying is, it's never too early to be paid, if you've got the chops. For me, the ability to demonstrate paid professional responsibilities in church music for about a decade by the time I finished undergraduate was and continues to be hugely helpful in successfully applying for jobs.

I probably wouldn't have applied for pay at my own parish, but all circumstances are different. If you would feel comfortable at your present skill level applying somewhere else for a paid, entrance-level opening, I would say that you should at least try to negotiate a title for yourself beyond "Volunteer" for use on your resume in the future. I would probably not personally want pay from my own parish, but maybe they would allow a certain stipend for lessons (it sounds like you already have practice privileges), which would be I think very appropriate. Possibly the MD (you didn't mention having private lessons) would repay in kind by taking you on as a student?

Play for pay ASAP if you can; I would apply out-of-house for that. Also, landing a job on your own ability rather than connections is good for you.

My son was just 14 when he started playing the organ for Mass at our parish. He was a pianist at the time but quickly adapted to the organ. He went on to take organ lessons and continued with piano as well. He was paid from the beginning which was only just in this situation. When he left for college last year, his younger brother, at age 16, took over for him as organist and does get paid as well.

So much depends on the specific situation. If the parish has been paying an organist before you, they should continue by paying you. If you volunteer to replace a paid organist, you will end up feeling the parish is taking advantage of you and it can get unhappy very quickly. If you are the first organist, I still think you should be paid something, maybe not a lot, but as long as you are playing through the Mass and do what's expected, this position deserves compensation. If you just volunteer, it tends to diminish its value in the eyes of the parish.

Can you have an honest talk about this with your pastor or whomever is your supervisor?

If they don't pay you now, they never will. You will have established yourself as a volunteer, which is just peachy for them. Having got you for free, it would never enter their minds ever to pay you. You may come to think 'I'm getting sort of good, surely it will occur to them that I should be paid'... but it won't and never will. Thus is the voice of experience and observation. If you are good enough to play for mass here or anywhere, you are good enough to be paid - just like the secretary, the plumber, the architect, the book keeper, the house keeper, the vestment maker, and everyone else.

This isn't necessarily true. When I first started organ lessons, my organ teacher was playing three Masses per weekend at the church I attended and sang in the choir at. At some point she decided to just do one Mass. The Saturday night Mass went to a vagabond Folk Group and she pitched the idea of the priest of me being the "intern" "interim" whatever organist at the early Mass. Maybe 3 months into my run at the early Mass I received a letter in the mail with a check and a note from the priest saying they would begin paying for my services and that I shouldn't discuss this matter with the other musicians (AKA "don't tell your organ teacher we're paying you").

Here's another option: if you will be playing each week, you could give one or two weeks free and get paid for the other one or two weeks. For example,
though I am a trained musician, I lead a chant choir 2 Saturdays a month. The first time per month I give to the church free, as a contribution since it is my parish and I'm not involved in anything else. The second time per month I am paid.

give one or two weeks free and get paid for the other one or two

It is a bad idea for a job
to have some work hours reported to be paid
and to have some work hours not reported
because employee decided those work hours would be volunteer.

The parish must budget and pay out the real amount.
Any other arrangement forever hides the true cost,
and creates precedent that neither you,
nor your successors,
can easily overcome.

Write the donation cheques.
It makes a difference in the mind of others
whom you might not think to be part of the situation.

EDIT: Plus there is ACA (obamacare) hours reporting etc.