Usually KD is recom as one of the last option in a child with drug resistent epilepsy (DRE): A new therapeutical point of view should be a new option in a infant?
As far as I know ketogenic diet is adjunctive therapy and usually cant be used as the primary therapy for epilepsy in both age groups. many researchers suggested this option only if the second and/or the third AED has failed to control the seizures.... furthermore, up to date there is no reliable evidence to prioritize ketogenic diet over AED for seizure control.
Usually when you use KD, after 2/3 AED, spende more than a year and it is too late to improve Neurological outcome. This is an evidence in some specific diseases as GLUT1, and KD as first option become first therapeutic option.