I would take what you can get. If an availability for a day you want comes up in the meantime, you can always cancel. We are checking into the Polynesian tomorrow, and I was unable to get 'Ohana for our arrival night (it was the first reservation I tried for, as soon as booking opened). I did book it for later in the week just to be able to have it, although I really wanted to eat there on our arrival night. I got on the TP reservation finder list, and actually received two notifications of availability during the past 60 days, but by the time I logged in to book it, someone else had beaten me to it. Sooo disappointing, but glad I at least I have the reservation I was able to get. On another note, being that you're going in September I doubt you'll have any trouble; good luck!