Hi 95zsean. Welcome to the ECF. You will know when too much happens. If you get sick feeling in the pit of your stomach, headache those are the two that are my dead giveaways that I need to put down my PV for a bout an hour. I typically vape between 4-9ml of liquid per day, most days right around 7. I have been vaping for a long time and have worked my way down from 24-30mg to 4mg. When I vaped high nic I would typically use about 5ml per day. It was my body that told me when and how much to drop down. As the months went on I would get sick feeling, not like drunk puking sick, but more of a general yuck and I would get really mild headaches, this was my cue to drop down my liquid strength.
Most importantly if the 24 that you are currently using is keeping you off analogs then thats what you want it to do for you. Also keep in mind that the stardust uses more liquid, more readily than a carto with filler. Keep up the good work. Good Luck. Happy Vaping.