The time for good opportunities is coming to an end, because bitcoin prices start to grow and as soon as people realize that the time has already passed and they could not buy ETH at cheap prices, a serious race will start.
I think there's always a good time to buy Ethereum. He always grows and rarely, as today, falls. But I can say one thing, it has not yet broken through its bottom and is unlikely to allow it, so 400$ is the minimum price you will see.