A: well, that depends on the sexual maturity ( or when all their sexual organs are fully developed)

Usually buy its 4-8 week they can already start breeding, but WAIT! It does not mean they are ready to be parents! Hamster mums whom are very young may not have the ability to take care of the babies!

Thus if you are considering to breed, make sure they are at least about 7-8 weeks before breeding them

Additional precautions you can make after she has given birth is to cover one side of the cage to give her that extra privacy