Was there a specific event that influenced the author's decision or mindset before going to Shirdi?

Yes, Chapter 2 describes a significant and tragic event that occurred right as the author's trip to Shirdi was being arranged. On the very day he was supposed to depart, his mind changed. This was influenced by the experience of a very close friend whose healthy and virtuous son was suddenly stricken with a fever in Lonavala. Despite trying all human remedies and even having the boy's Guru sit near him, the son ultimately passed away. Seeing that this terrible crisis could not be averted even with a Guru present seems to have been a powerful and sobering event that coincided with the author's own impending spiritual journey.