I have a studio for 4 nights in October. I called at 7 months and got it - in fact I actually moved my reservation two times - I didn't know how hard it would be and while I knew I wanted Sat - Wed, I had several weeks when I could go in Sept and Oct. So I started with the first week in Sept - got it. Then waited until the first week in Oct I could go - got it. Then waited a week and finally got the week I preferred - Oct 16-20. Each time I called right at 7 months. So it didn't seem too difficult if you call right at 7 months.
Now you are looking for a 2 bedroom which actually might be easier as I think there are more of them and a different time of year, so your mileage may vary as they say. And I do agree that it will get harder after they sell out. But I think we are OK for bit longer, maybe even up to a year since it will probably take a bit for the new owners to plan their first vacations.