Congratulations! We look forward to hearing how other tweaks (water drip, EGR, timing advance and increasing nozzle size) affect your system performance.
On the issue of starting up with used charcoal, poking through my nozzle is usually enough. If I want to be sure, I use a small screw type earth anchor to spiral down to the bottom and lift the old charcoal away from the nozzle then I use Kristijan’s pointed and perforated vacuum nozzle to suck out ash and dust from the loosened charcoal. Although I haven’t tried this yet, it has been reported that using your blower/fan to suck some fresh little pieces through your nozzle will do the trick.