I'm not sure why no one has replied to you. Have you figured this out yet? I would say wait until the roots are 4 to 5 inches long and then transplant that keikei!
New growth will come from the base of the plant - a keiki up on a cane.
If a keiki - it isn't necessary to remove it - my V-R has a few on it - some have sufficient roots that I could remove them, but I'm waiting til the keikis start a second growth. or bloom, or both ...
I think Den keikis may bloom sooner if left on the parent.