it's not just hunger, it's the stress and disruption of your physical and mental abilities, within 1-3 weeks, depending upon how bad it is. The livestock and grain will be gone the first month, the wild game the next month, the dogs and cats the next month, the fish and known about wild edible plants in another month. google for an almanac and see how much food the US IMPORTS. then check how much food YOUR STATE imports. Big piles of grain in Nebraska do you no good at all if you are in seatttle or nyc and there's no transportation. have you watched "naked and afraid? because the men are bringing in the firewood and building the shelters (foolishly) they lose 1.5-2 lbs of body weight per DAY. And they are finding/catching SOME food.
Local grain, bought in season from the farmer, is 50c a lb, guys. Molasses and salt are dirt cheap. Hard winter wheat keeps basically forever. Powdered milk is dirt cheap and you can rotate it out. do NOT count upon hunting, being seen/heard is highly likely to get you shot, post shtf. People will want to take your stuff and eliminate you as a potential threat. instead, think in terms of NIGHTIME tending of your fish, turtle and crawdad traps, your gill nets, seines, and trotlines. Pine inner bark and acorns, dandelions and cattails are all abundant, can be harvested at night, and the "booty" hauled off to distant, safer locales, where it can be dried and stored, safe from insects and rodents. Enough see to grow a TON of sprouts is very lw, compact and low cost. YouTube has many videos about this.
You'll only have other troubles if you lack the good sense to stay underground, except for nightly, short term excursions to dispose/hid of wastes, acquire water, and occasionally, access a food cache. you don't want much, if any food inside your little dugout, because the scent of it will attract cats and dogs.