What do you think will be the bottom for Bitcoin, from which it will begin to recover? Another question is whether now is the best time to invest or whether waiting for more dump is advisable.
If someone can predict the dip, for sure he won't tell anyone and if someone really can, he could also predict the next all time high.
To answer your another question, the best time to invest is when you trust your technical analysis about the next dip, if you happy about the dip, buy it, if not, then don't. Though hesitating so much even though you've done your part will give you only regrets at the end, sometimes not. For me, when you bought at $17,600, it's not that bad because that far enough from it's last all time high.