One way to understand this Delphic Maxim is to consider he bias of hindsight: we all have a tendency to perceive the past as having been easily predictable. Saying to someone after the fact, “I knew it was going to happen all along” is not giving them good advice.
Timeliness then is the key. If you decide to give your advice to someone (whether they have asked for it or not), make sure you are also giving the recipient enough time to process before making a decision. For when we give our counsel to another, we are trying to influence and outcome. Then we also bear the burden of the consequences.
Therefore, the Wise, seek to provide options to those who seek their advice. Provide them with thought exercises about the possibilities neither too far ahead so that they can be forgotten nor too late as to be unhelpful.