
If the mother had been wormed through pregnancy then I would wait to do them again for at least two weeks from when they were done, taking it to 4 weeks and then do them again before leaving.
I only ever do mien at 3 - 3 1/2 weeks and 7 - 7 1/2 weeks but the Mum will have had her 25day dose during pregnancy and first days after whelping.
I had problems when I followed the 3 times regime with puppies, and went back to doing them twice as vet had advised previous to having data sheet from manufacturer.