I will tell you from firsthand knowledge and experience on the inside (yes, I am currently in first year of the UQ-Ochsner program) that timing is of very little importance. The school is indeed trying to expand its class size every year, and trying to grow the Ochsner cohort as well. I know from experience that if you don't make the numbers, they will not accept you and in fact did not fill the desired number of spots for my current cohort as a result. However, if you are close they will likely give you the nod since they are in fact looking for cohort size. Once again, timing is not at all an issue. I have friends in the cohort (from this year and last) who applied in late september and got acceptances in November and even one in December. So apply but be ready to move fast.
Also, keep in mind this is a fledgling program. I cannot and will not go into details here, but pay attention to the fact that this program is currently NOT approved by the Australian Medical Council and as such if you are accepted there is the theoretical chance you will ultimately do all 4 years here in Brisbane. However, things are looking good and it truly is in everyone's best interest to see this go through. We are all working hard to get it done. Basically, what I am really getting at is be aware of the program's fledgling status, be prepared for the inevitable hiccups that will result from such a new and uncharted endevour, and be willing to be flexible. If you have that, and a serious hunger to succeed, then by all means come on down! I will honestly say that I was a bit disillusioned by the reality of those statements when I arrived, but I still feel that this program can and will ultimately prove better than a Caribbean school.