a stitch in time or a stitch in time saves nine
said to mean that it is better to deal with a problem in its early stages, in order to prevent it getting worse
The saying `a stitch in time saves nine' is never more true than with a boat's paintwork: one must be immediately ready to touch up the chips that occur in order to prevent a bigger job later.
Easy Learning Idioms Dictionary. Copyright © HarperCollins Publishers