If you mean preparing for a bear market then it is hard to pin point the exact date and time, duration and the coins that are involved. It is not something like a storm that we can see where it lands, or the gust and it's velocity. This is a crypto market here, we are talking of unpredictable moments, it's like an earthquake that strikes whenever it want to. Preparing is not seasonal in here and it should be on a daily basis, even traders out here spend their time analyzing graphs and they sleep less just to make sure to capture every inch of the details.
Many people use the stop loss feature just because of things like this, in these situations it keeps you safe. I personally do not use it because I am a long term holder, I like to make as much profit as possible in plenty of years and do not care about short term losses. However, not everyone is like me. So you could use stop loss for it.