How old does my puppy need to be before he can have a parvo shot?

Most breeders get shots at 5-6 weeks. My vet likes to follow up with another every 2 weeks. Most vets follow a less intensive schedule closer to the AVMA guidelines. It only takes one shot, but to protect the puppy it must come between when the any immunity from the mother wears off and 2 weeks before the puppy is exposed to parvo. For additional reliable information on this, see Canine Parvovirus, What you should know about

I'm not sure about about the one shot protection-we always started no earlier than 6 weeks (immune system won't accept the killed virus of the vaccine any earlier) and gave a series of 3 every 3 weeks. I guess every vet is different. Parvo is pretty bad in Texas.