It is something you can do - but.
You don't have to vaccinate to be NPIP. In most states, NPIP only requires that blood tested birds be free from Pullorum/Typhoid.
What state are you in?
Once your birds are tested, you can't bring in new birds until they are tested.
What were you considering vaccinating for? Most vaccinate for Marek's but that isn't required for NPIP.
Some states require a couple other tests like highly pathogenic avian influenza (HPAI) and MG. You can vaccinate for those but I'm not sure I would recommend it. They may show up on a blood test.
A positive blood test for HPAI will require every bird on the property to be euthanized and a quarantine around your area.
You vaccinate in a wing with a needle and syringe. Most vaccines aren't expensive but are sold in 1000 dose quantities. Excess can be frozen for later use but is usually thrown away. Bantams are very hard for inexperienced people to vaccinate because they are so small and the needle will go right through the wing and won't innoculate.
