At which verbal phrases during the Tashahhud is the raising and lowering of the index finger legally prescribed?

Etiquettes of Prayer: Finger Gesture, Supplications, and Other Adab

• Raise it at "Attahiyyat" and lower it at "al-mubarakatu".
• Raise it at the negation "La ilaha" and lower it at the affirmation "illa Allah".
• Keep it raised during the entire sitting.
• Pointing the finger is prohibited in the Hanafi school.