I am sure you saw the same things I did, but just in case, the most common thing people seem to say is along the lines of...
"Based on our research, we feel that pure, 100% linseed oil poses little, if any, toxic threat to human health, even though it does emit an odor as it dries.... Raw linseed oil is, in fact, flax seed oil. It takes a long time to dry but is entirely non-toxic"
Drying time will depend on your humidity and how thick you apply it. I'd probably put it in the coop once it is dry to the touch and does not smell strongly anymore. Maybe a week