Can you add baking soda to other dry ingredients in Step 4, or is there a reason it’s added with wet ingredients in Step 5?

I would mix the soda with the dry ingredients to be sure it's well incorporated. I haven't tried the recipe, but checked 3 online recipes for "Texas Sheet Cake" (Allrecipes, Tori Avey TastesbetterfromScratch) and all of them combined the soda with the other dry ingredients first.