Hello i vape 2-3 mL a day on my new gs air and i stick 20w. I havent changed coil as of yet and i am a new vaper. I have never changed a coil. From your experience when do i change the coil on gs air with this vaping a day. I exhale less vapor but still its not that few. At the store they told me 20 days but i feel like its dying. Thank you