Don't know much about danish oil but I do remember crosote in use and still have some very old inherited floors the had been treated with this on all surfaces. They would be painted in it over autumn winter and allowed3-6 month weathering before use and the bees never seemed to object so Dani's advice about leaving it over winter will be fine, as it is no where near as potent or pongy as crosote. Would be wary about doing sooner as if you can smell any odour, imagine what it will emit when warmed up to internal temp and humidity in the hive.