It's kind of the same as with mammals, sans the milk production, but anywhere from 4 weeks to 4 months a mama chicken will stop 'taking care' of the chicks. She'll want to roost(sleep) with the flock again and start laying eggs again. She may even peck at the chicks to make them stay away from her. With your single adult bird, it's hard to say what will happen at weaning time.I hate to ask such a stupid question but what do you mean by wean.
When the males become sexually mature, around 3-4 months, they will try to dominate and mate with all the females and fight with each other. Mama bird will probably kick their butts, but it's not a pretty time.Would the hen be alright when the chick roosters will only be a few months away from being young males?