The best time is the time you have set and you take off profit when it reach that.
Unfortunately, the price won't always reach the target. Sometimes, after buying and setting a specific price as the target to sell, the price of the coin drops constantly. Some people can feel frustrated and decide to sell immediately. Because of this, I don't want to specify a certain time as the best time to sell. In my view, when we sell our coin, should be the right selling time. The right time or best time isn't only determined by the number of profits but how important it to sell the coin at that time.
You need to have some different target at which price you are going to sell your coin. Depends on how many percent of profit you are willing to get. Lets say you set your target at 25% 35% and 50% profit so you need to divide your asset into that 3 target. Once you reach the lowest target then you can change the higher target based on the latest market condition.
In case the price dropped constantly after you bought the coins, you can do CL if you see that the price if going to drop again and again so you can buy it again with lower price. I have to agree that the best time is not based on the profit, the best time to buy and and sell is the time when you know that it is the right time to do it based on your own researches and strategy.
Every trader has their own strategy, target, and limit for their trading activities. The most important thing is, spend your money wisely and do not use your main money for trading if you are not ready to lose it.