How / when to treat

[RosyChickens]

My 8 hens were all hatched in feb, they are my first chickens, and everyone is doing and looking great. Is there regular preventive care I should be doing as far as medication? -deworming or anything?
Everyone looks good to my ignorant eye, but wanted to keep it that way. They are free range with layer feed , and oyster shells available.
And a picture of Foxy just cause
If it matters: 2 cymanis, one golden sex link, 1bantam Cochin, 1 polish crested, and 3 silkies

 

[Perris]

Prophylactic medication leads to resistance. If they are all well and good, celebrate it, don't medicate them for something they haven't got.