One other thought. Coffee itself contains considerable oils as much of the natural flavor. These may not vape completely and leave a residue, and might not be good for the lungs too! If you are detecting irritation in the lungs or lots of coughing, this might not be good. And at the very least I would be tempted to having a dedicated cart/atty for the AM vaping. Sort of like I have a dedicated cart/atty for mints and menthol.
Personally, while this may be ok, I am not comfortable with having caffeine depositing into my lungs. We know about nicotine, we don't know about caffeine, although not a lot is likely to actually get to the lungs, depending on the fluid thickness. Thus it seems just drinking coffee would be more efficient and certainly with less safety concerns. But hey its your call, of course, so let us know what the results are!