Also, treats mustn't exceed 10% of their diet so I would try giving it to them when you let them out
One potential benefit of treating your hens early in the morning is that depending on how BADLY YOU "TREAT" your hens that maybe they will run some of the treats off before it is time to give them real food. Whole corn is not a treat, whole corn is a viable chicken food on par with any of the other foods mentioned in the title of this thread. Just because the anti-Monsanto click bad mouths maize is no reason to not feed it.
This seems to have started when High-Fructose Corn Syrup cut into the market of European sugar beet growers. Therefor this is no reason to not feed whole, un-cracked corn or American Maize to your chickens. Just do it within reason and with the understanding that there is NO BEST OR PERFECT food for either man nor beast, not even God's own Manna from Heaven.