Custom Security, best practice for integration?

Article piece from

Custom UserStore/RoleStore and UserManager

and github code in https://github.com/radzenhq/radzen-examples/tree/master/CustomSecurity

shows something that appears identical to what we need to implement.

From experience, what is the smoothest/painless way to integrate this code with a radzen prototype?
Complete the prototype so no more work needed on that side and then try to integrate the custom sscurity code?
Start "dymmy project" with default security, integrate the custom code and then build the rest?
Etc.

Any experience appreciated.

Cheers.