When to use "best glide"?
flingwings has more than a grain of truth in his comment about avoiding best glide tricks.
When should you use best glide?
After the successful transition to a good autorotation - rotor in the green and steady, pedal trimmed, speed about right,
and after the turn toward the wind.
and only when you realize that the ONLY good landing place is too far away, and little else is usable, at all.
Then, you bend over to best glide, set the aircraft up, and see if you will make it. This is a test, and recognize it as such. A test to see if you really can make that far away alternative.
Can you make it? You can tell easily once you have stabilized in the best glide, because the place where you will hit the ground is the only place on the bubble that stays in place while every other place slides up the bubble (too far) or down the bubble (close enough).
How do you know if the far away place passed the test? The place had better be moving down the bubble, cause all your prayers won't make the helo go one yard farther!
And if the place is OK, plan to get into it, past the edge, and be too steep on it, cause you can burn off height.
If the place is not ok, too far away? Just slow back down to best ROD, turn toward the best bad landing area, tighten your shoulder harness, and get ready for loud noises.
Does Best Glide speed really make a difference? Yes, absolutely, Try it next time you are out.