Key facts: earliest displacement is 4th century; earliest attestation is circa 200 AD in traditional spot

The earliest example of verses 34-35 being placed after verse 40 is the Ambrosiaster from the late 4th century. The earliest manuscript of 1 Corinthians (P46, circa 200 AD) has the verses in the traditional location. Scholars also warn that removing passages found in every single manuscript threatens the integrity of all scripture -- there would be no principled basis for removing any passage you dislike.