Keep track of where it has been; you don't need to buy at the absolute lowest point, if it creeps back up you can slowly buy in again.

Have a look at trackers like the S&P 500 after previous crashes, it takes 3-6 years for the market to return to its previous highest value. Or six months in the case of the panny-D crash.

Experts also do not know the answer to that.

One way to do it is pile into something with strong fundamentals you think will survive.

Be the first into a rowboat that’s not leaking. Others will join you.