Nikon's explanation can be found here:
Nikon | Technology | VR (Vibration-Reduction)
For your lens, VR should help you at 1/250 of a second at 300mm, but shouldn't be needed at 1/1000 of a second. In fact, there is advice from several sources to turn VR off for any shutter speed of faster than 1/500 sec.
Of course, Nikon's sheet also caveats that VR effectiveness is dependent upon the photographer's skills, and is based upon the premise/example that the photographer can "get it right" 70% of the time before seeing a 70% chance of four-stop hand-held improvement. I take that to mean that if the photographer has a 10% chance of getting right without VR, then they have the same 10% chance of getting right with the VR engaged at four stops slower exposure speed.
Either way, your technique is extremely important to the final outcome, and VR cannot be depended upon to create great images. If you have questions about how they do it, read up on the subject, and the next time you visit an event, go early and try to find a pro and ask for a few pointers. Most will be very happy to provide a few tips. Just don't get in the way of them doing their job, i.e., don't ask them these questions during the event they are shooting. Just try to observe them during the event to pick up on their techniques.
WM