You do not have to give tetanus before you disbud but some people do. And yes, you can do them on the same day, but I usually don't do CDT until at least 3 weeks and I have to disbud much earlier than that, usually no later than 10 days.
We got the girls disbudded. Not the best experience. But they are doing great. And we think we did it right. Got the good copper ring but we didn't knock the cap off. DH said the instructions didn't say too.