The petition for adoption may be filed at any time after the child who is the subject of the adoption is born, the adoptive placement determined and all consents or relinquishments that can be obtained have been executed. The hearing on the petition may be held no sooner than forty-five days after the filing of the petition and only after the child has lived with the adoptive parent or parents for a period of six months, proper notice of the petition has been given and all necessary consents or relinquishments have been executed and submitted or the rights of all nonconsenting birth parents have otherwise been terminated.