Transcription initiation is the phase during which the first nucleotides in the RNA chain are synthesized. It is a multistep process that starts when the RNAP holoenzyme binds to the DNA template and ends when the core RNA polymerase escapes from the promoter after the synthesis of approximately the first nine nucleotides. Once RNA polymerase is in position at the promoter, the next step of transcription—elongation—can begin.
