Yes, straight away (well, as soon as I was able to check anyway!) - mine was really light and was pretty much down to spotting after a fortnight. Not sure if that's just my body or if the surgical team did a really good job of clearing me out!
Lochia is the wound site where the placenta has left and also a general clear out of debris. C sections don't necessarily delay it or make it lighter, every case is different regardless of birth method.