I like making soups and porridges. I usually add salt and pepper at the beginning to add flavor. Recently, a friend gave me a bottle of soy sauce and Im experimenting with it.

What would it make more sense? to add the soy sauce with the other ingredients before the mix boils, while boiling or only to add it before serving?

Another question is: should I use salt if I use soy sauce? Apparently, this sauce has a lot of sodium.