as the matter of fact, you don't have a specified time to or sell, but you have to do is to have to patient till the coin grows.... e.g wen you buy coin of $2000k and you never sold it paraventually the price decreases to $1000k will you aford to loose that 1k or you will hold till comes up to that your $2000k beforeyou sell. that is the same principles holding others, they may like to hold till the price comes up before they will sell.