She could whelp any time between 63 - 68 days along depending on when she was breed. Keeping track of her temp is one of the best ways to tell if your gal is ready or getting close. Take it twice a day and get her whelping box ready like Now !!
This site should help you, its very informative and Deb is very knowledgable.
Canine Reproduction Video and Book on Breeding and Whelping dogs by Debbie Jensen for dog breeders and Whelping Supplies needed to deliver puppies.