It hasn't really started yet... the shrimp will puff up around the same time it is releasing the most amonia. That's when it really starts... The amonia goes up, then down, the nitrites go up, then down, then all is well (except that you'll want to do a water change).
As far as chromis go, they don't mix with eels and lions, they'll get eaten. But if you want chromis instead, a group of three would probably be ok. Again though, keep watch on the water quality and make sure you have a skimmer.