Configure your Case detail page to display the relevant fields from the Case Flags package:

• Flag or Flag (BH), depending on your organization's use of business hours 
• Initial Response, which is a date/time field, and thus business hours agnostic
• Initial Response Hours or Initial Response Business Hours, depending on your organization's use of business hours

Follow the steps below to add fields to your page layout(s).

1. Go to Setup | Object Manager | Case | Page Layouts.
2. Choose Edit next to the layout(s) you want to update.
3. Locate the Flag or Flag (BH) field and drag it onto your layout.
4. Locate the Initial Response field and drag it onto your layout.
5. Locate the Initial Response Hours or Initial Response Business Hours field and drag it onto your layout.
6. Click Quick Save.

Two custom buttons are available to manually clear and set the flag.

1. Within the Case page layout, click Mobile & Lightning Actions on the left, and drag/drop the Clear Flag and Set Flag buttons to the Salesforce Mobile and Lightning Actions section.
   1. For Salesforce Classic users, click Buttons on the left, and drag/drop the Clear Flag and Set Flag buttons to the Custom Buttons area of the page layout.
2.  Click Save.

Note: Adding these buttons to your page layout(s) will also make them available for use in Salesforce Mobile on your mobile device.