I'm not an expert on the answer which is why I'm asking, but I've been studying the topic the last few days as we have a big fire in Colorado now.
I've set the following guidelines for myself.
1. I won't go within 50 miles of a known fire. The second day often spreads breathtakingly fast and there is little information.
2. I won't hike or backpack into any dead end trails that don't have an alternate way out or a safe area. I define a safe area as a mountain lake above the treeline.
3. If I can see the plume of smoke, I'll start making my way to safety even if I have to hike further than I planned that day.
4. If I can see or smell smoke even from a large distant fire, I'll only hike in a few miles for an overnight trip. This comes from my experience with the Hayman fire which was 100 miles or so away. Breathing was uncomfortable when conditions were just right.