When to market? There is absolutely no solid rule, except one: Sell long positions immediately if the reason why for sale prove themselves to be wrong by declining in cost.
Good "buyers", in other words, those who learn how to recognize real bargains, tend to be weak "sellers" since they have a tendency to sell prematurily . or hang on too much time.
They either become uncomfortable the moment their positions reach "normal" valuations (sell prematurily .) or have a tendency to give their positions "the advantage of the doubt" when early signs of weakness commence to arrive (hang on too much time).
Periods of depression, bad business conditions, and public apathy are naturally accompanied by periods of overvaluation, good business conditions, and public over exuberance.
At such times as stock prices advance beyond probably the most optimistic expectations of these who bought very early and incredibly low linked with emotions . feel uncomfortable and unsure of these positions.