While your still a bit new to sharpening and you would like to make some coin doing it. I would suggest setting up at a farmers market, a special event, hardware store, etc., first. You can also have drop off locations in your town. This would give you experience and confidence dealing with different bevels and General knowledge of steel and knives before offering to kitchens.
Your hourly rate is way too low. I charge per knife. If they want to set up routine sharpening it's a dollar less per knife. Single and multi bevels are a bit more as is other equipment, mandolins, deli slicers, food processor blades, etc..
If something is hand sharpened I charge an hourly rate.
The problem I see with "per inch", is that a 6"-8" chefs knife will take longer to sharpen than an 18" slicer. Same goes for a small pocket knife that can be a real pain in the arse for $2.
Yesterday it took me nearly 4 hours to sharpen 26 knives. They were all neglected but well made western knives, single and multi bevel Japanese and several serrated. The day before (a place I sharpen regularly), I sharpened 80 knives in the same amount of time.