When should I use a Virgin Queen?

You want to see plenty of drones flying before trying to get virgins mated. People say that the drones need to be in the purple eyed stage at least, but that is when they are talking about grafting and the queens are still a couple weeks out. I feel you should see plenty of drones flying before you introduce a virgin. If your drones are flying, then the ones in the environment probably are as well. An exception to this could be if you are feeding your bees early to get them to brood up earlier. If you are speeding your bees up, you may be putting drones out there before other colonies are, and you may want to wait a bit longer before introducing a virgin queen.