It's going to be terminal C or D.
I don't think you'll be able to find out much before the morning of your flight, but, what's the difference, really? I'm in the limo business <tho, not in NYC>. You can just tell your driver which terminal when you're in the car. Even if you're dropped off at the wrong one, you can still check in there, and walk from one to the other after you go thru security - they're connected, and, it's maybe a 3 minute walk at most.
