Anytime is good time to buy BTC if you have faith on it and willing to hold it long time.
If just short time, maybe need to be good at day trade first.
I think no, there is right time to buy a bitcoin, the price is totally huge and it is not affordable in ordinary people. Since the price is volatile there is a time that bitcoin was dump, and it is the right time to buy because we always encounter the big decreasing and recover easily and pass the previous high price.