KyHills,
It's important to have the initial dose of tetanus toxoid on board at least a couple of weeks prior to banding older calves, and giving a booster at the time of band application. Or, giving a dose of tetanus antitoxin AND tetanus toxoid, then boostering the toxoid 2-3 weeks later.
I've seen trainwrecks with producers losing 15-20 head of big calves to tetanus over a few days' time when they gave tetanus toxoid at the time of banding... the lost the 'race' between the organism germinating and producing toxin and the calf's immune system responding to the toxoid and making antibodies against the toxin.