The informant is recounting a Chinese proverb from home. He does not remember where he heard it.
The cart will find the way round the hill when it gets there.
He interprets to mean that you should not worry too much about the future.
This reminds me of the American saying: “You shouldn’t put the cart before the horse,” meaning you shouldn’t get ahead of yourself and think too far ahead. They have very similar meanings and both relate to carts. They could possibly be distant oicotypes of the same idea.