Hi,
C02 should go ON BEFORE lights on. 1/2 hr min. I put mine on 90 minutes prior, as that is how long it takes my system to get to my c02 level.
But really up to you...........
C02 should go OFF PRIOR to lights off. I go about 30 minutes.
Do NOT use c02 when lights are off. Plants nor fish need it at this time.
I have extra pumps come on and off with the c02.
I do not aerate at night with anything extra than the normal filters/pumps.