As far as I am aware one must be within 1/2 scale deflection of the LOC to descend on the GS.
The only time I would consider descending early (subject to ATC) is when descending to MSA or descending to the published altitude for that leg of the approach.
Look at the numbers. If one is on the GS at the minimum altitude before 1/2 scale deflection of the LOC then I believe that there is a high probability of a rushed approach and/or an unstable approach.
Regards,
DFC