We are staying at poly 12/10-12/17 and I was wondering if it would be possible to walk up and get a table for 2 adults and 2 children for the character breakfast at ohanas if we go there as soon as they open?
I wouldn't hold my breath. I would, however, keep trying for a reservation as you get closer to the trip. Especially just after the 60 day mark when people are firming up their daily plans with FPP. Also, people will keep dropping reservations right up until the night before and sometimes day of.
Just keep looking. I know it may seem like nothing will ever open up but before my trip last November, I was able to get a Chef Mickey breakfast two nights before we flew down.
Use the reservation finder. It's your best bet. I didn't try to get 'Ohana but I got 3 other awesome reservations using it.
I would say the chances are slim, especially if it's pre-RD. Later in the AM maybe.