Again, so sorry. Typically the CD&T shot is given ~30 days before anticipated kidding. This protects the mom with the side benefit of the vaccine being passed on to the kid(s)/lamb(s).
"Vaccinating the pregnant ewe
2 to 4 weeks before lambing will result in protection/immunity to these clostridial diseases in the form of antibodies being passed on to the lamb via the ewe's colostrum, her first milk. This passively acquired immunity lasts for the lamb's first 50 to 60 days of life. Ewes lambing for the first time should be vaccinated twice in late pregnancy, about four weeks apart."
From:
http://www.extension.umn.edu/food/small-farms/livestock/sheep-goats/use-of-vaccines-in-sheep/
So the way I read this, I'd say, yes, go ahead an get the up and coming mommas vaccinated for CD&T now, and then when you give the lamb(s) their first shots you can do the mommas booster at the same time.
Real shame that there are bad vets out there, just like bad people docs, and with vets, there's really nothing to do if they screw you.