How are outposts supposed to be used exactly?

I think they're supposed to be used similar wards in league of legends. However, sending villagers to places that need to be warded will hurt my economy very much if I do it early. In the feudal age, where I have to watch out for rushes, warding costs stone so I won't be able to build more TCs when castle age comes without mining stone.

Do most people only ward during/after the castle age? Are there strategies that involve warding early in the dark and feudal ages? I understand I'm supposed to buy a ward, stop a gank, save a life but it's hard to do so without ruining my economy.