Everytime are perfect but its up to you when do you want to buy. Knowing that for now bitcoin is on low value ypu should take this chance to buy at low price. If you are lucky then you are!
I really believe that today is the right time for you buy bitcoin and ethereum while market price of both popular coins are decreasing.
I think the best time for me to buy is when the rate is down and hold for a good exchange rate. Patience will be your only hope to have for a good price, if you have funds buy coins as many as you can for a high possible profit in return.