Everytime is good time to buy btc or eth, it's just depend on what you are going to do with your btc or eth after you bought it. Long term holding for btc and ethereum is a good way to earn huge profit especially if you are going to buy now while the price is low. Many people always wait for more deep  but for me better to invest now and hold. And if there is more price drop then buy again as long as you have capital because opportunity just comes once. The scenario in crypto market is just cycle, there is a bear market and bull market. Bitcoin is already more than 10 years of existence which is a proof that it will become more and more valuable in the future.