I've had deer eating corn seedlings, so it will attract them right away. Even as the corn gets bigger during the summer, they will eat the leaves/stalks, and they really like to eat the developing ears. If you are going to plant corn and there is no other corn in the area, be prepared to plant large plots (5+ acres) or else you won't have much left come hunting season. Raccoons love to eat it as well. They can decimate a plot in a hurry.

One reason why I prefer soybeans over corn is because it can be browsed on by deer through the growing year and it will still put on more growth and develop pods. With corn, if it gets nipped off early, the ear is eaten off early, or it gets knocked over, that is it for the plant. I've had a 3 acre corn foodplot destroyed by deer and raccoons before season even started. I ended up broadcasting turnips in the corn so I at least had a late season attractant.

Just remember corn needs to be fertilized (especially nitrogen) or it will not grow well at all. Corn is one of the most expensive plots you can have.