Nobody on here will be able to give you a definitive answer. We chance walk-ups frequently at WDW and have had varying degrees of success but we always know we may be turned away. If it's some place we REALLY want to eat, we book an ADR. If it's a must-do, make the ADR. If you are ok with possibly being turned away, do the walk up. If you attempt a walk up, I would do it late morning to better your chances. Or simply check the app the night before or morning of to see what's available