A stitch in time saves nine is a well known all proverb. This proverb could lead us back to the 18th century. This very proverb literally means that when one sees a small tear in a cloth, it’s best to stitch that up rather than waiting for it to get bigger or keeping the work for later, for if it’s being tackled immediately it saves a lot more time.
In the broader sense, one could say it’s better to solve a problem or an issue right away, to stop it from becoming a much bigger problem because if this is kept for the later, the problem may develop and grow into a large complicated problem.
It’s a clever and witty expression to say that it’s better to spend a little time and effort to deal with a problem right now than to wait until later, when it may get worse and take longer to deal with.