If you haven't found an opening before then, that will be the time.
The three reached the point from which that came, and found an opening in the wall.
It would be impossible to find an opening through their line.
We have to circle the island and find an opening.
Finally he gave his horse its head, and the animal found an opening he'd not been able to see.
The Shadow took the turn; found an opening among the trees.
The two find a small opening in the cave but decide to keep going.
The others moved quickly, but with far more care, and found an opening in the ring of steel.
Harry turned away and found an opening between two tents.