Some day in the future, you will realize that the best time to invest was not today, but some other day in the future, when prices were low. But with the information that you have today, the best time to invest is still today, because you do not know when prices will be low, and you do know that the longer you hold your investment, the more time it has to grow.
Toughts?
If you set something thing like this target for any investment, you will never invest for sure. Because no one can predict when prices will fall or rise, so it is always good to start investment immediately when you decided with a small amount and start buying it in regular intervals so you buy price will be averaged out. If prices never go back to 50% less than current price then you only need to watch the price movement and never invest in it.