You must calculate your capital on that coin first, for example now the price has given you profit 30 % from your capital, i think that is good time to sell your coins. If you want more profit, you may wait for few days again. But, remember that the price can be bubbled anytime, try to satisfy with less of profit and not to be greedy.
That's a good idea, you must think if you will have a profit. But if you already satisfied with profit you want then you can sell it. But if you still twice about it, maybe just wait for the best time you want. The important is you have a profit, and just to contented it.
Some of the beat thing on it is not to be greedy on what you can also have to earn for cause there is a possibility that you may lose if you wanted to make more profit.