Bitcoin is back down to $ 7500 and altcoin is also following Bitcoin, is this to buy BTC when it is going down badly or waiting for the price of $ 7,000,
Obviously, things have changed since this post got published, but the time for buying depends on your intentions. If you mean to hold it for a few years, any time is good for investing. If you want to trade, then there are trading techniques that can help you make a profit with greater certainty of success.