Our calves get hauled away from the pasture when weaned.  Ideally we would go to each pasture and work them before we wean them but its really not feasible to do that to all the pastures as they are miles and miles apart.  We try to work them as soon as they step foot off the truck and then booster them 2 weeks later.  We have tried to wait to work them for a week and the year we did it, it was kind of a train wreck.  The weather sucked when we weaned that group and they were off of our heifers so there were more variables in that.  We will vaccinate off the truck as usual. If they are that close to home, I would try and vaccinate them first then wean in a week.