Priming a coil is important, but letting it sit just doesn't do very much, (in my opinion as always). To prime a coil you have to get some capillary action in the wick. I do "prime" my coils to start at 0 watts, without pushing the fire button at all, but the suction (I do it a few times) starts DRAWING the wick up into the coil, and as you then slowly increase the wattage, you'll have a full primed coil (thanks mostly to priming puffs, starting with no power).
If you run into issues, you could look into a thinner juice mix, and some coils do best (so I have heard) with a judicious poke or two with a needle to loosen up the cotton. But, I would try priming correctly without doing that first, and only try that if you run into continued problems.
I can let a new coil and juice sit overnight, I'm still gonna take some non fire button primer puffs, and that is what "starts" priming IMO.
Good luck,
Anna