Read the manufacturer's label recommendations with regard to age/stage of production, AND when to give boosters(if it calls for one, and you don't give it in the appropriate timeframe, you've pretty much wasted that initial dose).
Inforce-3 contains IBR/PI3/BRSV; no one has been successful in developing an effective intranasal BVD vaccine that didn't have some pretty profound adverse effects/reactions. I like the Inforce-3 vaccine, and use it preferrentially over Nasalgen or TSV-2 as the initial viral vaccine in my pre-weaning protocol.