The very first thing I doubted before ever coming across apostate material was the fanciful interpretation of prophecies in the "Revelation Climax" book. The notion that the seven trumpet blasts had anything to do with a series of conventions that no one alive today would remember always seemed ridiculous. I continued to wait patiently on Jehovah to provide new light on this.
Discovering that Jerusalem was not destroyed in 607BCE was the catalyst that led me to examine things further.