If there's a consistent price declined (about 50-60% of the price), the market is bloody, then we can say we are in a bearish trend already. It happened before and history might repeat itself but its not a situation to be worried about since thats one of the nature of crypto. But it doesnt mean it will stay that way forever, just be prepared and be used to it because its inevitable, sooner or later it will happen.
The market decline of more than 30% is possible that it is already in a bearish period and this will definitely be prolonged once the indications of bitcoin start, therefore this is not a definite place but we can see with our eyes and possible trends where bearish can be happen.
This bearishness can happen at any time, even when the market is stable, sometimes it reverses direction with its resistance, so I can confirm that a bear market will definitely happen, but whether this will be prolonged or not, we still have not determined.