Have you examined the relationship between your writing productivity and your habit of checking Facebook before you start each day?
I have. And when I check Facebook first, my productivity for that day gets cut in half.
In half.
Here's why. Facebook doesn't contain things important to you--it contains things important to others. If you start your day with messages, posts and comments from friends, your mind stops focusing on your creative work and starts focusing on everything else. Before you know it, you've squandered 30 minutes--or perhaps hours--on things other people gave to you to do.
Worse, you won't know the nature of the distraction until it's too late. Maybe it will be some joke someone posts. You respond, and it leads to a thread of messages back and forth. Maybe the distraction will come from some political statement that irritates you and puts you in a less creative frame of mind. Maybe someone says something wrong on the internet, so you waste your creative time "correcting" them.
Whatever it is, it will be something.
There's a better way. Don't let this stuff enter your brain in the first place. The point isn't to avoid social media. The point is to get some meaningful amount of creative work done before you look. Put your work first.