i have a similiar bamboo plant. The keiki should be left until i pretty much looks like a small plant
once the roots are 3 inches long, and there are some nice leaves, but off the stem about an inch along from the keiki and plant it in similiar medium to the mother. (this should be checked by another orchid grower
)
if the cane is just plain, no keiki, and the flowers have gone, i would leave it till it starts to go brown, and very stick like, then cut it off about an inch frm the bottom