I saw this posted in my topic, and although I don't know the answer, here is a free bump! Good luck, I'd like to know as well.
No minimum. I was given promo financing with an AAoA around 6 month's.
I would say it would be good to have a few accounts over a year old, two years would be better.
If you history is very short, expect a higher rate.
Generally, employment is key for approval. Credit history and down payment are key's for lower rates.