That’s definitely a good plan. I know I always get caught up in running as much as I think I can fit the first time. But tires don’t last forever, running a little bit smaller than what you think is possible and going bigger next time around is a safer plan for sure. And with tires nowadays even if you don’t wear them out you’re buying a new set in like 6 years anyway.
Believe me, I’m not sure if anyone could be more surprised than me about those 18x9.5” +12’s. And I’ve rolled my front fenders already. I may not have pushed them as much because I was trying not to pop my paint, but still!