The minimum age for a kitten to be delivered is at least 12 weeks. By that time, kittens are vaccinated, a microchip is implanted, and a veterinary doctor has checked them several times. If kittens are delivered from Europe, then a medical examination must be done before they can board a plane, and full medical records shall be provided to the US Customs.
We suggest that within 48 hours after you receive your kitten, you also take it to a licensed veterinary clinic for examination.”