There is a delay after every death cross. Historically, it took the following days after a crossover for the market to take a dip-
1st cross- 35 days
2nd cross- 2 days (minor fall in the prices)
I'm just eyeballing it, the dip could happen anywhere between 15- 40 days then after the cross takes place.
An 80% drop would mean were below 10k
EDIT- removed some speculative dates