They are juvenile up until about 7 months. After this they are considered an adult. You can't just sit by and hope they get tame. Because you bought so many of them, they are going to bond with each other first, most likely. You want to aim for them bonding with you. Buy a pair of thick gloves from Home Depot. When I got my pd I held her constantly with the gloves on. She would bite but don't let it phase you. They will want to try scraping out of your hands to run away, don't let them. Just keep holding them and petting them and within two weeks they will be tame.