The Arundaneria bamboos(tecta, gigantia and appalachiana), North American native cane have a 3 year growing cycle. The first year the culm grows to its ultimate height. It has a papery sheath at each node. The second year that culm matures, walls get thicker and more rigid.
At the end of the second growing season the papery sheath begins to deteriorate. After that second growing season is usually when I harvest, generally in January or February.
During the 3rd season the papery sheath is all but gone and the culm changes from a bright green color to a more olive green color, still good for arrows. By the end of the 3rd season the culms die and turn tan color. I don't harvest cane that turns tan color while still in the ground.
Other bamboos have different growing habits so a little experimentation is in order but by the end of the second season is probably a good time to harvest. I've noticed that if I do cut immature culms they seem to shrivel as they dry with longitudinal wrinkles along the surface.
Once you've harvested cane, lay it in the sun to dry. The exposure to the sun will turn the canes to a tan color so rotate them while drying to get an even color. They will eventually turn tan on their own.
I like to bundle a group of like sized canes(about 15 to a bundle) and hold them with rubber bands. As the canes dry they shrink and the rubber bands shrink with them, keeping the bundles tight.
Like with bow wood, seasoning is the key to stable shafts so the longer you can season them the better.