We have been to Ohana 2 times and both times waited about 20 to 30 minutes to get seated.
If we have a reservation at 3:35 is the wait still long since dinner time starts at 3:30?
I've had an ADR for right at the beginning of dinner (but back when they started dinner at 5:00) and were seated without a wait. As PP said, just check in before 3:30 and you should be seated right away.