Don't forget that they need to still be on medicated feed when they go outside (as mentioned above) for the medication to work. They need exposure to the soil and potential bacteria in it while the medication is still in their system, so their immune system can learn to fight the bacteria in a...
Agree that ideally they need to have been outside for a couple of weeks before you wean them off of the medicated feed. But it won't hurt them to eat it past those couple of weeks, so if I were you, I'd get another bag of medicated, and if they've been outside for at least 2 weeks by the time...