25+ plus yrs of planting corn for critters
all I can say is, HOW soon they will eat corn, depends on a ton of factors
from how many deer are in your area, to what other feed they have to eat.

I personally love to mix soybeans into my corn plots, when NOT using a seeder to plant(as I don;'t like mixing corn and bean seeds in my hoppers, would wait till one runs out then re set up for other seed)
but if you disc your seeds in, mixing in soybean seeds, will make your plot very attractive faster, deer like to eat beans when growing and then when they get more mature, they lay off till they dry off then come after them again
this will allow time for the corn to grow and start ears before they start to eat it

the beans in the corn will make the corn thicker and the deer tend to come into my bean/corn plots a LOT sooner in day time, due to they feel safer in the thicker cover!, heck many times they simple bed in it!

for a few yrs now, I was making islands inside corn bean plots
say take a 3 acre or larger plot (about what one bag of corn seed would plant) and do a 70x70 yard patch in the middle of JUST beans, then rows of corn and beans all around it

great place to stick a blind in there then, and NO one ever knows where I am hunting as cannot see middle of plot from outside
at my place deer will eat corn from the time its planted(dig seeds up) to when it harvested
typically have 6+ acres of corn/ corn beans mix for food plots and every other yr 60 acres of crop corn on one property!
have way too many deer there, so they eat everything as soon as they can till its all gone LOL