One place to find the answer to this question is on p. 100 of Guns, Germs, and Steel. This is in Chapter 5. The information can be found in Table 5.1. There, we are told that Egypt was the first place in Africa to get food production. We should not be fooled by the fact that Egypt is farther down on the list than the Sahel and West Africa. Instead, we should look at the dates in the right hand column and note that Egypt was the earliest date of domestication.
Egypt is lower on the list because the Egyptians did not invent agriculture on their own. Instead, they domesticated local species, but only after founder crops had arrived there from Southwest Asia. People in the Sahel and West Africa might have come up with food production on their own at a later date, but the place in Africa that got food production first was Egypt.