I tried the broomhandle method and it can work well, but turkeys have fairly weedy necks and it is all too easy to pull the head, or indeed the head and entire neck clean off! I recommend stunning (airgun or back of an axe both work well) and cutting the throat from ear to ear, or remove the head completely with the bird hanging upside down to bleed for 20+ minutes. Apparetly, new legistlation says you mustn't start plucking for the first couple of minutes in caase they're still alive, but that's unlikely anyway as they're flappig like crazy to start!
I hang mine for up to 10 days, guts in. It takes a couple of days for rigor mortice to pass. I would never hang once drawn other than in a very cold fridge.
Plucking can be wet or dry. If dry, as Womble says, it's easiest straight away, or after they've been hung a good while. Wet can be any time. Plunge in really hot water - not boiling but certainly more than hand-hot - swish around and keeep it there until you can pull out a flight feather on the wingtip easily. I prefer dry plucking. Apart from risking damage to the skin, wet plucking is messy and smelly, but certainly quicker than dry.