DIYmg, if you have any room light, your plants are photosynthinsizing (sp?)…(not fat fingers, I just can't spell, lol). So, that's why it doesn't matter WHEN your plants are doing that, just that they are when your co2 is on.
In CA we adapt our light cycles to cheaper (or solar, me!) power. It all depends on where you live & your cost of power at any given time of day...it's not apples & oranges everywhere, you have to do the math