Good questions. I would leave it in primary for the entire time, and bottle it when the taste is to your liking. It will get more sour the longer you let it go, but 9 months should be a good amount of time. May might be a little early for the oak, but again, how much oak you'd like is personal preference. I'd let it bottle condition for a month at least, but after a couple weeks you could try opening one to see where it stands. Let me know if you have any other questions!