Just look at the graph:
Yellowing usually requires about 2 days for lower-stalk leaf, but may require up to 5 days for upper-stalk leaf to yellow. After that, it's exactly 3 more days. That's all. It does benefit from airing, after it cools, and is returned to a moisture content that allows you to handle it.
All of this is discussed in great detail in the threads on flue-curing (see Key Forum Threads).
Bob
Yellowing usually requires about 2 days for lower-stalk leaf, but may require up to 5 days for upper-stalk leaf to yellow. After that, it's exactly 3 more days. That's all. It does benefit from airing, after it cools, and is returned to a moisture content that allows you to handle it.
All of this is discussed in great detail in the threads on flue-curing (see Key Forum Threads).
Bob