It is always bad time to buy a coin when it is rising you should buy it if everyone is hopeless about it and sell it, ~buy always when there is blood.
I think that is a general perception and the logical reasoning is also needed to be discussed. Besides, this is true only about an asset with great potential in its early ages Right now, when all the coins in the market have reduced values and very low prospect of growing anytime sooner, I do not think you should invest in Waves. Better change your mind and go for something else. ETH, Litecoin and Bitcoin are great alternatives.