The KIS soil pack says its ready to USE in 48 hours after mixing? that cant be right man. ill have to look on my pack,Ive never seen that before bro. But IMO even if it says that,I would not use it that soon. . .Ever to be honest. its still cooking hot,and high microbial activity and still blending. Ide wait minimum 30 days or until the heavy fish compost smell dissipates largely. but it typically go 45 days or even 60 days until I use it generally. but 30 works alright. but again,. Id not use it that fast. not saying a sprinkle over the top of the stuffs wont work,its just ,thats not how to use this pack. and for tier planting.
any soil is fine it just has to be delicate of fluffy enough and mellow enough for auto seeds,which are more hardy these days generally speaking. so your recycled soil thats been used and not been amended at all. or some seedling mix is what I typically prefer but either will work.