Where in the book does it describe the moments Sai Baba physically held the pen to write his own story for Hemadpant?

The text does not describe any moment where Sai Baba physically held a pen to write the book. The statement in Chapter 2, "I myself shall enter with 'I-ness' and write with my own hand," is presented as a metaphor for divine inspiration and grace. Baba clarifies this by saying the author, Hemadpant, is "merely a pretext" and that the work will be accomplished by Baba himself once the author dissolves his ego and surrenders at Baba's feet. The writing is therefore understood to be Baba's work in a spiritual sense, flowing through the surrendered devotee, not a literal, physical act of writing.