Twenty plus years user of EC stacks. Less is more. I get better results with less, would recommend 8-16mg daily. The appetite suppressing won't be quite as great as say 25mg, but you won't get jitters. You'll get a noticeable increase in strength with 16mg, but I don't notice much past that.
Your body adapts to EC pretty quick. Higher amounts push you to the limit faster. Save your money and preserve the stash. I'd recommend a caffeine amount but I just can't take it anymore, keeps me up all night no matter what time of the day I take it now.
My cardio routine is pretty intense, I'd never take it on days I have a lot of cardio planned.