Long time lurker, first time poster, hello! 
I searched all over this forum for this but found nothing, I apologize if it's already been posted.
It turns out that you can tell how charged the waft is by looking at Wario's shirt... it slowly lifts up and will show more and more of his stomach as the charge increases. It maxes out and stops as soon as Wario starts to glow brown.
It's actually quite visible (even at a distance) if you know what you're looking for. It seems like this would be a better way to gauge when to use the waft than just estimating... I've been able to use it at near max on opponents without keeping track with a stopwatch.
NOTE: As far as I can tell, this only works on the "Biker Wario" skin, not the Classic Wario.
I searched all over this forum for this but found nothing, I apologize if it's already been posted.
It turns out that you can tell how charged the waft is by looking at Wario's shirt... it slowly lifts up and will show more and more of his stomach as the charge increases. It maxes out and stops as soon as Wario starts to glow brown.
It's actually quite visible (even at a distance) if you know what you're looking for. It seems like this would be a better way to gauge when to use the waft than just estimating... I've been able to use it at near max on opponents without keeping track with a stopwatch.
NOTE: As far as I can tell, this only works on the "Biker Wario" skin, not the Classic Wario.