Help please.

[ElephantU]

I've never toyed with Food routes that early in the game. Before AD1, try to select city sites that maximize growth for making more settlers. A site like you suggest should only be worked when you can set aside a few spare workers to improve terrain, maybe even improve a couple "helper" cities devoted to extra food production.

 

[Ace]

That is usually correct, but not much use if the land you have to work with is limited in good city sites. I don't recommend this method if better city sites are available, I just mentioned it as a possible use of food caravans.