Guy's what do you think, 55* water temp. Shock or wait till it gets warmer?
As long as you have the pump running shocking now is easier. Chlorine works a little more slowly at cold temperatures, but algae grows way more slowly at cold temperatures so the whole process is easier now.
It's perfectly normal to have zero CC's even when algae is present. In outdoor pools the sun burns off th CC's as fast as they're generated.