Personal experience never add shrimps and start adding CO2 or reduce Co2 coz u will cause a PH swing which will surely kill the shrimps. Keep the tank stable after u add shrimps do not make any changes. My tank CO2 goes off at night buy I have a PH controller also my tank is well aerated, I'm using a stronger external filter which aerates the tank water at night.
Many hobbyists claim that RCS, yellow, rilis, CRS, Tigers, etc do not reproduce as often as they do in non CO2 tanks.
It is possible to add CO2 during cycling period but other things like light w/g, water changes, fertilizers should be taken into consideration. After tank is cycled slowly reduce the CO2, Lights w/g and fertilizing only when the tank is stable add live stock.