No one can say for sure what will be with the market and when we will see some grows. So, play it safe - decide which price is comfortable for you right now and buy ETH, but do iteratively with some time lag (for example a week). And each week revise your comfortable price zone. If price higher, then just wait for the appropriate time.
Basically, you need a strategy. It will help you to eliminate impulsive actions and give confidence. But don't forget to adjust your strategy periodically.