Last time I made it I just tasted it for saltiness before fermenting and it came out great. Another thing worth knowing is that right when it is done, it's good, but you put it in the fridge and it tastes batter and better. I don't know if the flavors "settle in" or what but it certainly gets tastier.
Feed it to mom/ rinse for you, and make more with a bit less salt?
I can tell mine is fermenting by smell, it starts to smell like kraut.