If you haven't found an opening before then, that will be the time.

It took three days, but he finally found the opening.

The three reached the point from which that came, and found an opening in the wall.

It was on the way back that he found the opening in the ice.

He must have found the opening into the next domain.

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.

Following the tracks, they found the opening into the mountain.

With little trouble, they found the opening of the deep chamber.

The others moved quickly, but with far more care, and found an opening in the ring of steel.