1 to 1.5 hours to reach your target temp? You have a lot more patience then I! I always love to read everyone's methods and how they do things differently. Thats what makes this site great!
If it's anything like my 18.5 (I still havent done a burn-in yet on the 22 ---- stupid latch screw anchor came out when i tried to install it on the cajun bandit door), then using the method we just outlined, I usually was up to temp within 1 hr, but typically got to atleast 175 within 20 mins tops. It was from about 180 to 220 ish that took a while.
Remember, BBQ is not something to hurry. I learned long ago to make a 4hr window for large cuts (butts, brisket, etc) and 1-2 hr window for something like ribs. That way I never have to rush anything. Simply put, getting a good put environment established takes a bit of time.
If you dump 50 lit briquettes in on a Minion-method charcoal bed, you're doing 2 things:
1. You're inserting WAY too much red-hot heat in there. Each of those coals is likely at peak heat. Would you dump 50 coals into a Weber kettle if you wanted to cook steaks at 225 (hypothetical) ??? Heck no! 50 briquettes gets a kettle RAGING at 600F or higher.
2. You're letting the lit fuel completely ruin your Minion method because the WHOLE coalbed is now lighting up, instead of slowly radiating outwards from the donut hole towards the donut.
Make sense?
Finally, another option to consider is getting the 18.5 charcoal ring. My 18.5 isn't being sold for another couple weeks, so I may try that once I get my initial 22" burn-in done.