Dave, I pretty much do it just as Schmoe describes it, above.
In the M16, you want to get it up to 100 rrpm before pulling the stick all the way back, because a strong ambient wind can cause a bit of flapping when it's less than that – so you don't want the rotor near the prop/tail just then (hint: keeping the stick forward and to the right minimizes this early flap).
On the M16, as it turns out, the rrpm is the same as the tip speed in mph (28ft x π x 60 = 5278 ft)
I usually get to 100 off to the side of the runway, then bring the stick all the way back as I turn onto the runway and into the wind. Turning into the wind usually helps spin it up up to 200 or so pretty quickly, at which point I disengage the prerotator and start my takeoff roll. Keeping the stick all the way back, I bring it to full power pretty quickly. When the nose gets light (i.e. rrpm is nearly sufficient for flying), I move the stick forward just enough to keep the nose from popping up, continuing to build airspeed while maintaining the rrpms. At that point you are trading off increasing the rrpm for increasing the airspeed. As Schmoe says, at about 65mph it just starts climbing away nicely, without any new stick input.
