Amazon began developing the Fire phone and the Echo around the same time.

True: credible accounts date the start of Fire phone development and of Echo development to roughly the same period, within about a year of each other (both around 2010–2011). Mostly true: the start dates are about one to two years apart but both are in the same early-2010s phase. Mostly false: the start dates are clearly separated by more than about two years. False: the evidence shows clearly different, unrelated timing, for example Echo starting years after the Fire phone launched.

Set before the research began.

1. E1 Excerpt from "Amazon Unbound" by Brad Stone Scribd (excerpt of Brad Stone's book)

   “he emailed Hart, device vice president Ian Freed, and senior vice president Steve Kessel on January 4, 2011, linking the two topics: “We should build a $20 device with its brains in the cloud that’s completely controlled by your voice.””

2. E2 Excerpt from "Amazon Unbound" by Brad Stone Scribd (excerpt of Brad Stone's book)

   “The smartphone market had shifted and matured during the painful four years that the Fire Phone was in development, and what had started as an attempt at creating a novel product now seemed strangely out of touch with customer expectations.”

3. E3 Learning from Mistakes Penguin India blog (excerpt from Jeff Gothelf and Josh Seiden's book Sense and Respond) · 13 June 2017

   “Motivated by consumers’ increasing use of mobile devices, Amazon began the Fire Phone effort in 2010, just as the iPhone 4 was hitting the market.”

E3, an independent book excerpt, says Amazon began the Fire Phone effort in 2010. E2 says the Fire Phone was in development for four years. E1 dates Bezos's founding email for a voice-controlled cloud device, the Echo concept, to January 4, 2011. That puts the two starts within about a year of each other, in the 2010–2011 window the criteria give for a true verdict.