According to current theory AIUI, cosmic inflation greatly influenced the CMB. It ended approximately 10^-32 seconds after the Big Bang:
"Cosmic inflation is believed to have occurred in an incredibly brief, rapid, and exponential expansion phase lasting from approximately 10^-37 to 10^-32 seconds after the Big Bang. During this minute interval, the universe expanded by a factor of at least 10^26, and potentially as much as 10^50."
"Cosmic inflation is believed to have occurred in an incredibly brief, rapid, and exponential expansion phase lasting from approximately 10^-37 to 10^-32 seconds after the Big Bang. During this minute interval, the universe expanded by a factor of at least 10^26, and potentially as much as 10^50."
Quite a theory, cosmic inflation...