Practically and obviously, the best time to sell or trade your tokens is when the market value is at its peak because it would result to huge profit. But what's sad at this moment is that, the market value of tokens are suffering from continuous downfalls which makes it hard for investors to trade and sell their holdings knowing that they would earn nothing from doing so. Holding also at times like this would be stressful especially for not seeing positive changes in the market as a whole.