As strange as it may sound, I think the crash will come if there's a change in the white house or congress. Most investors fear the unknown. At least with the current administration and congress, we know what we are getting. The market is already nervous so I suspect once we get to October we will start to see a lot of market volatility caused by the feeling of who is likely to be president on any given day.
I know how to prepare. I'm saving money, so when all of the stocks drop, I will invest.