The lateness of your adsr could help you. 9 pm is late for some people to eat. I am different in that this (or later) is my usual dinner time. My adrs are usually for this time or later. I have eaten at Ohana this late and found the wait short (provided you arrive at or before your adr time). Ohana does not like late arrivals for adrs. (it could severely lengthen your wait or get you denied altogether). I think your wait will be much better than those with adrs in the peak dinner times.
But - as with everything in disney, relax and go with the flow. Its impossible to predict what you will get. If you do have a wait, make the best of it - get a drink from the bar and settle in and enjoy the atmosphere of the Poly. I especially recommend the lapu lapu.