Welcome to AFN. I'm going to move your thread over to the New Growers forum where we can better focus on helping you through your first grow.
Generally speaking, most of us avoid using any Miracle Grow products, especially their soil. They are not friendly to growing weed and can be difficult to manage at times. At 4 weeks your plants are still in pre flower and won't go into full flower until about week 6. While they are in still in veg they should be feed a nutrients that is higher in N. Everything you have now is for flowering. Also, bear in mind that the feeding schedules published by the nute manufacturers are for photo plants, not autos. In general autos are a little more nute sensitive and require less feeding than photos.
Take a look at this thread. It will give you a better understand of what to expect from your autos.
https://www.autoflower.org/f44/life-cycle-auto-flowering-cannabis-5113.html