Im quoting from my "the dog owners vetinary handbook" here:
The bitch should be wormed before mating, at or after 45 days pregnant, a day or so after whelping and every two weeks after that untill the puppies are 12 weeks old, with a larvicidal wormer from your vet so that any worm larvea migrating through her body tissues will also be killed.
The puppies should be wormed at two weeks of age and thereafter every two weeks untill they are twelve weeks old. Worming should continue at four, five and six months of age.
After this ALL dogs should be wormed every three to six months.