I think a bank pin is a great idea, and an extra layer of security. I would like to see this added sometime in the future.
However, I don't think a 3, or 7, or whatever, day wait is intelligent for it to be set, removed, or changed. It should take place immediately, and for changes, you must know the old to set a new.
Forgotten passwords should be sent to the person's private email. So don't set one unless you have a private email.
Just my thoughts.