About IDF revision

Sir, first of all thnak you for this site its very helpful.

Sir i want to ask that
1. how to do idf bill revision for rural/ village consumers... Is there any criteria to take minimum unit per month.

2. If jee/sdo submit report after inspection of site is consumtion is max 20kwh per month then can i revise that idf bill on 20kwh per month?

3. First we should install meter on site after on month on meter record kwh consuption ko hi bade maanke idf bill revise kre?