I waited 6 weeks before adding my cuc. 25% of what was recommended. As far as the Nassarius snails they will clear detritus, uneaten food, decaying organics, and fish waste. They also help maintain adequate oxygen levels in the substrate as they burrow and sift through the sand. I keep about 30 in my tank now. For my tank a cuc has been essential. I have a heavy bio load. My cuc crew doesn't add to it, they help balance it. Tanks have personality IMO
. Start slow, be patient. It's part the tank build process.