Depends on the plane and the weight of the plane.
In the 747 I drive, when we're light I start to pull the power off between 30' - 50' depending on the conditions and then start flaring at just over 20'.
When we're heavy, I start flaring at about 30' and leave the power on until the flare attitude is nearly settled. At weights inbetween, I do a bit of a blend.