I'm going to apply for PR to Buffalo soon. I've heard that after a certain stage of processing I can change employer without work permit requirement.

Is it the case? What stage I should pass in application to be actually able to work without applying for work permit?

Thank you.

The only type of application that would have any such bearing on work permit eligibility would be an inland spousal sponsorship. For other applications submitted to Buffalo, Skilled Worker for example, this would not be applicable.