Place all the wet ingredients except for lemon juice (or milk will curdle) in a mixer bowl, and add the coconut flour. Mix well. Let rest 20min. so the flour can soak up liquids. Meanwhile, preheat oven to 400°F. Line muffin tins. Whisk together remaining dry ingredients in a bowl, set aside. After 20min have gone by, mix the lemon juice into coconut mixture, then add the dry ingredients into the wet. Fold in the blueberries. Bake 20 minutes.