i have my tank cyclying so far for 2 weeks with live sand and rock i also have 4 damsels in there which would start the nitrogen cycle. how do i know when the cycle is finished and what should i put in when that occurs?

you will need test kits. get yourself the ammonia,NO2 and NO3 test kits. a mormal cycle will have elevated ammonia level,then it dips and yr NO2 levels will rocket up. the NO2 will then taper down with yr NO3 levels going up.

yr tank will be fully cycle when the reading for all 3 is zero but remember to stock slow as every livestock u add will start a mini cycle again.