If you are not going to be moving the plants around or distrubing the substrate then I would start EI right away but use like 1/2 dose. and increase slowly over time.
If you do a lot of rescaping then I would hold off for a few weeks or more and just Add micros and K.
Be careful with your CO2, with ADA Substrate the KH/PH chart is useless.
it will lower your PH, KH, GH. How long and how much depends how your original tap water params and how many water changes and how often and how well you vacum the substrate.
My KH out of the tap is 3KH and my ph sits at 5.5ph. if I were to follow the chart I would have 285ppm of CO2 but the fish don't show any signs of stress.
And be very careful in pulling out plants that have a good root system. I have spent many many hours trying to get the powersand back underneath the Aquasoil.
So many folks rattle on about how great it is, well, in some respects, but the two layer approach has trade offs and I don't like the low density, goes flying all over. Takes longer to do the pruning.........
Add the white sand front and any terracing over the long term........you know what is going to happen and folks can say whatever they want, we all know it's going to mix.
unless someone wants a special effect in the looks of their substrate,it makes more sense to purchase something like soilmaster,i think they come in three different colors, and get the long term benefits of a much less expensive substrate. AND you don't have to worry about root'n in your tank changing things later,and we all do that.we are all looking for simplicity,that saves $$$ ! regards,cornhusker
let me tell you what I did years ago as to avoid mixing the two layers of aqua soil and power sand. When replanting I always cut the stems right above the substrat surface which left the complete root system untouched. Never had any problems with the rotting material. This might have been due to (don't read this, Tom) the strong heating cables (30 watts for a 20g tank) I was using at the time. Rather, I speculated the remainder of the decaying roots helped new plants to even grow better.