I only deworm when I see a need for it. If they seem underweight or if I see adult ascarids in their poo. If I suspect that they have worms, I run a fecal exam. Chickens are meant to carry a certain parasite load. My chickens free range, though, so I'm sure they self-medicate. I used to deworm my horses every 3 months, but now I only deworm them if they have a positive fecal exam. Overuse of anthelmintics and insecticides can create resistant strains of these parasites just like the overuse of antibiotics can create super-bacteria. I have a friend who puts DE in her food and coop, I think it makes things really dusty. She takes care of my horses and she feeds her own horses DE, but not mine and neither of our horses has had a positive fecal in about a year, so I'm not sure that DE is really necessary. Besides, I have a feeling that DE could be harmful to beneficial insects and worms as well as the harmful ones.
I would just feed them, make sure they have fairly clean living spaces and fresh water. The best advice I can give you is to know your birds, know their behavior and if there is something off, ask someone about it. Keep a first aid/medicine kit with terramycin, sulmet or corrid, wound powder and triple antibiotic ointment, vetwrap, and betadine or chlorhexidine. Don't overthink chickens. But, when its nasty out like it has been for weeks on end, I would go with medicated starter and definitely, preemptively purchase a bottle of sulmet or corrid to keep on hand, just in case.
I would just feed them, make sure they have fairly clean living spaces and fresh water. The best advice I can give you is to know your birds, know their behavior and if there is something off, ask someone about it. Keep a first aid/medicine kit with terramycin, sulmet or corrid, wound powder and triple antibiotic ointment, vetwrap, and betadine or chlorhexidine. Don't overthink chickens. But, when its nasty out like it has been for weeks on end, I would go with medicated starter and definitely, preemptively purchase a bottle of sulmet or corrid to keep on hand, just in case.