The only pre-treatment I've done is using First Saturday Lime in the cracks, crevices, and nesting areas of my coop. It doesn't prevent your chickens from getting mites, but it will slow them down from setting up shop in there. I retreat every couple weeks after a deeper clean.
If/when you do see evidence of mites, switch to treating the coop with permethrin garden and poultry dust. Same concept, but with insecticide.
I'm not a fan of permethrin spray for chicken stuff. It's unsafe until it dries, and needs regular reapplication (especially if it gets wet). I do use it on my garden boots though! Nothing beats permethrin for keeping ticks off you.
