We have been eating bread since at least 10,000 BC, and probably earlier. Beer came probably about the same time.
The great thing about grain, is that it is easy to gather more than you need for one meal at a time, and it is easy to store.
It's difficult to understand the rise of foodstuffs that came before writing, and even possibly before the development of agriculture.
The way Tom Standage (A History of the World in 6 Glasses)^1 reconstructs it, cereal grains were first eaten as a gruel, rather than ground and baked into loaves. This gruel, if it was left out, would have fermented into an alcoholic beerlike beverage. Later Mesopotamian brewers could control the color and taste of their beer by adding different amounts of bappir, or beer-bread, small cakes of malted, sprouted barley which were crumbled into the beer and had the advantage of being able to be stored for a long time. There is much debate between archaeologists as to whether beer or bread came first. I can't say there is a definitive answer, much less a definitive date for either, but I think it's likely that the two came pretty much around the same time, and both were derived from the early grain gruel that was the way we believe early grains were consumed, as a thin gruel could be left out to ferment, and a thick gruel could be baked into bread. Basically, they were the same thing: bread was liquid beer, and beer was solid bread.
Some scholars take this even further, and suggest that the prevalence of beer and bread from wild grains provided the impetus for domestication of those grains, leading to the Neolithic Revolution and the development of "civilization".
Other studies have put human consumption of grains as far back as 100,000 years, based on residue analysis of ancient stone tools (Mozambican Grass Seed Consumption During the Middle Stone Age, Julio Mercader Science 18 Dec 2009 pp1680-1683). Since agriculture (the development of a way of controlling and propagating the growth of useful plants) has been around since approximately 10,000 BC, and we know that grains were usefully consumed far earlier than that, we have to assume that the gruel, and therefore the bread and the beer occurred well before 10,000 BC. I can't give a better estimate on that score.
Wine is probably similar, it's not quite as old as beer, but it has been around since the dawn of civilization, as people left fruit out until it fermented, or left its juices out until it fermented, and created wine.
Cheese also predates writing. The oldest evidence we have for a cheesemaking process comes from 6th millennium BC Poland, in the form of lipid residue analysis on pottery..
Milk-producing animals, such as sheep and goats, were domesticated between 11,000 and 8,000 BC, based on what we can find from archaeological sites, evidence from the animal bones, and artifacts dealing with domesticated animals. When people began to utilize these animals for milk as opposed to fibers and meat is uncertain, but certainly early. Most ancient legends with regard to the beginning of cheesemaking give its discovery as someone storing milk in an animal's stomach, and the rennet in the stomach separates the milk into curds and whey, creating a form of cheese. This is an extremely plausible theory, given that stomachs and bladders were automatically watertight things that you could store liquids in, which was a necessary innovation.
Therefore, all of these foodstuffs have been in use for far longer than recorded history, some since before 10,000 BC, and all certainly before 5000 BC.