With my buttons, I've just been leaving them under the light until I'm ready to pop them into their adult enclosure, and this has been working well for me. Chickens are a good bit larger though, so it would be easier for me to pull them whenever I can. In doing a quick search, I couldn't find anything on when to pull lights from the bantams. I know, I should have it etched in my mind from research beforehand, but I don't.
Any help would be appreciated.