Now is the time to buy Bitcoin, as their further growth is expected. If you have free money, you can invest it in Bitcoin and just wait for it to grow. It makes no sense to twitch and try to earn on fluctuations. Cryptocurrency will reveal its potential only in the future by 2020.
How can you know that? What if that doesn't happen? Or maybe you are someone who believe to Jhon McAfee's prediction? There is no one will know appropriately when the best time to buy, when the price will goes up and when the price will goes down or even for some expert who predict it never say bitcoin will ONLY reach the price at specified years.