Somehow I think I've written the following before...
Demonstrating the incipient stages of Vortex Ring State is the RW equivalent to stalling a FW airplane. You learn what the symptoms are in training, and then learn to avoid it for the rest of your flying career.
I have only ever been able to get the symptoms when entering at sufficient height AGL (more than 2,000' AGL, just like stalling), and from a downwind condition. Start at 60 knots, reduce the power slightly below the power to maintain level flight at 60 knots and decelerate maintaining altitude. At about 20 knots, the first symptom will appear (low frequency airframe vibrations). Next the aircraft may (and note the may) exhibit uncommanded pitch, roll and yaw (i.e. don't move the stick or pedals and the aircraft wanders around). Not always repeatable. Rate of descent is 500- 1,000 fpm. Adding collective may or may not increase the rate of descent (not always repeatable).
Recovery is by smoothly, but positively lowering the nose about 20 degrees below the horizon and flying out of it. Safe to do as described.
Learn the symptoms and recover at the first sign of the symptoms.
Any time the induced velocity equals the airflow coming into the the rotor disk, something has to give. The induced velocity (the downwash velocity if you will) is not uniform across the disk when hovering, so the effect will probably start at the hub and move outboard as power is increased.
Something that should be done on transition to a new type, and at a later stage of PPL training as well, just so you remember it. Doing it too early risks losing it in all the other stuff you have to remember.