Actually from my experience from last one year it is very very difficult to predict what is the real time to buy BTC or ETH. It is all out of control i think. If you think you will buy now you can take a risk and luckily you may gainer or loser.
That's correct there's no perfect timing to buy or get involve but we should know the process and risk. But when it comes to principle we should buy at low and sell at high then bitcoin is good for long term hold we need to invest our time and patience to become success.