Running 10 guage fused wire to stereo head unit, suggestions?

What point should I drill through the firewall to make the shortest possible wire run to the rear of the center console?

I plan to route from the battery, around the engine bay on the passenger side, and run through a hole drilled in the firewall close to the rear of the head unit. Im going to grommet, sheath and stay it thoroughly so I never have a short.

There is already a rubber plug in the fire wall by the heater valve. You can just pull it out and drill a hole in it smaller than the wire. Fish it with a coat hanger and pull the wire through. The plug is big enough to run several lines and no leaks. It comes in under the the heater and behind the rug on pass side. I have 1 4gu, 2 10gu and 2 or three 12 gauge wires w/ no prob. Best of all no metal drilling . P.S. run the wire you need inside first then it is a shorter pull in the eng compartment.