Since you mention kilning, I'll assume that you are asking about home-grown leaf.
You can select wrappers at any point along the way. If selected after kilning, then the leaf has likely endured all the processing damage, so safe storage is all that's left.
My simpleton approach is to assume that any fairly intact leaf may make a good wrapper. Each crop of each variety will differ in its burn, stretch, flavor, appearance--differing from one growing season to the next. Sometimes, while setting out some leaf for immediate use as filler, I stumble into a pretty leaf that I use instead for a wrapper.
The more cigars you've rolled, the sharper your eye will be at seeing a promising wrapper.
Bob