Personally, I think an 8:30 -8:45 reservation at Ohana is the perfect time and would never choose anything else, but that's just me. They dim the lights and pipe in the Wishes music, and do the kids activities right after. You'd never catch me in there at 6, but I digress....
If they don't have one already, you will soon see a Cancelled thread for the month you are going, where people will post the reservations that they have cancelled. My advice is to stalk it daily and look for someone who has cancelled Ohana.
For adults and older children, yes that's wonderful. But with an infant, not so much.