Believe he is referring to Instant Detailer and Gloss Enhancer
OP- Ideally you want as clean of a surface as possible before putting a protection product down. Using ID before OS *could* reduce adhesion and durability. I would use those the other way around, after OS has cured
You can layer them back and forth , but I would lay down the OS first. After that you can layer OS and OID back and forth as needed / wanted . All these products bond together nice IMO.