Hey guys, I'm very new to vaping. This is actually only my second day of no cigarettes and just vaping. Anyway I had a question regarding e juice. I currently have a 6mg juice in my tank and its almost gone still a bit in there though. I have a juice of a different flavor that I want to put in there but it's 12mg. Is this possible?? Should I wait till the old stuff is gone completely?? Thanks!