I do not believe that this feature is available at this moment but please do file a suggestion to the Suggestion Box

There are no direct way to set a home page. That being said there is a way to get the same effect.

• Make sure that the page is in your history
• Tap in the address bar
• Search for the history item
• Long press on the history item
• Select "Add to home screen"
• Use this bookmark shortcut to launch Firefox.

Thanks! that's a great work around.