Like Bill said, topping with it shouldn't be an issue at all as the plant roots can choose whether to populate it immediately or not, and that will depend on how hospitable they find it. The issue comes when you mix it into your soil and the roots have no choice but to be in the middle of it. And that's not even an issue if the soil is fully cooked. If it's not, then the heat created by the microbes breaking stuff down can fry the roots.Would nutrient burn be an issue with topping of with the super soil? Or would temp shock the pots? It has been raining since I got up, and outside temp is 54.
That's why in The Rev's organic growing methods he puts spikes of pure amendments down into the pot at up-pot, but outside where the roots are initially. The spikes serve as a nutrient bank for the microbes to use without burning the roots.