The best way is to play a sine wave of the resonance frequency of the speaker. It should be loud but not too much to destroy the speaker.
The resonance frequency of the Wizzard 8 ohm is 89Hz, 16 ohm 100Hz.
If you can't produce the sine wave you could play music through it, but make sure you have bass to move the driver. The goal of breaking in a driver is to loose up the suspention. The parrameters of the driver will change once the suspention is loosened up and then will be pretty well stay stable.
Recommend a solid state amp, not tube, for breaking in.
The time will depend on the driver, but about 8 hours is good.