12 weeks of age: Administer the third combination injection and possibly a lyme vaccine inoculation. Generally a lyme vaccine is repeated two weeks later, then once a year. 16 weeks of age: Adminster the last combination vaccine. 12 to 16 weeks of age: Adminster rabies vaccine. The timing of this vaccine may depend on the laws in your area (since this can be a human disease, too). Confirm with your veterinarian and check your local and state laws.