This isn't really MC...
Depends on the look one's trying to achieve, style of jacket, ect
If you like rules thumb whatever, if you would have the jacket with just bare skin underneath it would not show none or very little of your belly when worn. I usually like the jacket to be just under the belt-line, rather than closer to the top.
I think sleeve length is more important to the overall look. Seeing a leather jacket being worn showing inches of skin above your wrist is rather comical.
EDIT: Your jacket looks nice. I personally wouldn't worry about the 1 or 2 inches or whatever below belt, especially if you have jeans that actually fit at the waist instead of sagging. If is was 4 or something may be more concerned with a jacket of that style.
+1 to post a fit if you expect more detailed/specific answers.