The complete course of home whitening usually takes about 3-4 weeks for a desirable effect. White spots seem to be an absolutely normal sign during the whitening process. You should not be concerned about that.
Since you were not aware of this side-effect of whitening, I am assuming your daughter is using an OTC whitening product. When you whiten your teeth, it is quite common to see all the inconsistencies within the enamel as the teeth dehydrate from the whitening product. Keep in mind that these inconsistencies were always there and will disappear once again when the procedure is completed and the teeth rehydrate. As stated this is a very common occurrence with whitening and something I always discuss with the patient before treatment begins. Good Luck!