I haven't been invaded yet. I don't stay embered.
Nothing wrong with that. My 1st playthrough I wasn't embered much, beyond starting boss fights for the buff. I imagine you will be eventually invaded. Right after P.S. boss. Don't want to spoil by naming. Killing the boss gives an ember, then right beyond the boss is an area people are always pvping in. Ember + PVP area right after = invade. In addition to that, you'll get a mandatory invade if you're embered and move through that area, but by two computer characters.