Anyone that said there is no withdrawal when using ivermectin is misinformed, and anyone that said you could put the pour on in water is also misinformed because it's not water soluble.I had the same question, and 3 different local chickenkeepers said no withdrawl period (it was for adding the pour on ivermectin to water for ingestion as a yearly worming) and I'm still hesitant myself, as I am still treating my coop for mites and didn't want to stress them with both poisons, and I want more input from those with more knowledge.
Would be best to use permethrin spray on both the chickens and the coop. If you don't want to disturb your broodies, use the ivermectin topically.