Don't take her to the farm. You do not know what foxes, coyotes, and un-owned canines have been on that property and whether any have had distemper or parvo. Don't take her.
As to shots, I am in the same boat. I have a pup coming to me and the breeder (who is just starting out on a breeding career) vaccinated the litter at 6 weeks! I am NOT thrilled. I will be having to do three sets. What I did is took the # of days between shots and 16 weeks & divided by 3. That gave me 24 days per. I just scheduled shots 24 days apart until we finish at 16 weeks and then rabies alone a week later.
The shots are not exactly null and void, they diminish as the mother's immunity kills them. So either the shot or mom's immunity has them somewhat protected. As long as shots are 3-4 weeks apart you are partially covered as you inject and mom's immunity kills it or not (at which point the shot serves). However, you don't have the immunity to go places like pet stores, camping, dog parks, walking around the neighborhood, places with canine wildlife.
I hope this helps. I would take the number of days between the shot and 16 weeks and divide by 3 and just keep giving them. You will need 3 more sets and the final one has to land on or after 16 weeks. Rabies should be given alone after 16 weeks.
Cara -- Central CA
+ Shay -- GSD
+Melody Rose & Cubby Shelties