Your pullet is going to be in for a very hard time in a week or two when his hormones kick in. She will not be mature enough to breed but his hormones will be raging and he will be mating her forcefully and repeatedly and any noise may more from her screams than his crowing. You need to make some decisions fast as things could get unpleasant quickly. Whilst it is possible to keep breeding pairs together on a 1:1 basis, a young immature pullet and a rampant young cockerel are not a good combination. You will start to see her lose feathers off her back neck and shoulders and her skin become raw. She may also suffer gashes under wings or be scalped. Young cockerels are best kept separate from pullets or at least be kept with enough pullets to share the burden 10:1 pullets to cockerels will usually ease the damage but some will still get overmated. Finding him a new home or keeping him in a separate cage or coop is the best option if you do not have space for more chickens. You also need to check if roosters are allowed in your area as many residential/urban areas specify female poultry only.