The sketching part usually takes me the longest, since I'm not technically good at drawing (I get it like I want eventually, but it takes time).

The coloring process is faster, since I think I had a talent for that, but the way I use the copics - with lots of layering and blending - takes a lot of time. I'm guessing maybe 8 hours on coloring this. But it is just a guess, I tend to get in flow while drawing, so I don't really pay attention to the time XD