Trusted friend personal tax account

I am in the process of registering as a "trusted friend" of someone. How long will the process take after they confirm I can act in that capacity? What happens after they confirm I can act in that capacity? Will I receive confirmation and instructions about how to access their personal tax account?

I have established for myself how to do this after the person I am helping confirmed they had accepted me. It's disappointing that no one from HMRC replied.

Hi 

Once accepted as trusted helper with online updates it  can take up to 3 working days to update to our different systems. 

Thank you