When should users be notified of a pending password expiration

1. What period of time is recommended for password expiration?
2. How to notify Office 365 users that passwords will expire?

What period of time is recommended for password expiration?

In this day and age, changing passwords every 90 days gives you the illusion of stronger security while inflicting needless pain, cost, and ultimately additional risk to your organization.

How to notify Office 365 users that passwords will expire?

Set password expiration policy

In the Microsoft 365 admin center, go to the Security & privacy tab. If you aren't a global admin or security admin, you won't see the Security & privacy option. Select Password expiration policy.