That's easy to answer. When bitcoins are going up, you're better off holding onto them as long as possible. If you're a buyer, you should buy a week or two before you want to spend on drugs (if you did that during the recent climb, you'd get twice as much drugs for your money). If you're a seller, you should wait one or two weeks before cashing out (if you did that during the recent climb, you'd get twice as much money for your drugs). When bitcoins are going down, or they are unstable and unpredictable, you're better off getting rid them as soon as possible, so at least you get close to the value you paid for them.