The million/billion dollar question is when will we hit market bottom. A lot of traders and short-term investors are feeling the heat right now.
Ironically, bottoms are often hit when investors capitulate. If you're fully invested, the usual benchmark for when the bottom is hit is when you finally give in to that feeling that you're going to lose everything, and it's so painful that you just can't take it, so you throw in the towel and sell everything. I don't see capitulation yet. The sell-offs still feel somewhat orderly and gradual (though rapid).
If you're waiting on the sidelines with cash, it's often better to not "catch the falling knife", but to wait with buy-stop orders that trail the market, so when the rally occurs, yours is one of the first orders hit. Of course, when any rally appears, there will initially be a trickle of buyers, and then a stampede. It won't be easy to get a great price on a stop order that fills at the market price during an explosive relief rally.
No matter where you are, it's never useful to sell into a panic unless you sell a little bit ("throwing a maiden in a volcano") to give you mental breathing room.
Now is a good time to assess what powder you've got dry, and look for the opportunities. The opportunities will usually not be in the previously hot sectors. A stock screen using low P/E won't catch the drop-off in earnings expected in many companies that were booming last year. However, if you add low price to book as another screening criteria, then you might find better quality issues.
Volatility rewards those with patience and a clear mind ...