Normal gestation is 58-63 days. Around day 60 you will want to start taking her temperature daily when it drops to 99 or below you should expect to have puppies with in 24 hours.
She may not eat if she feels labor coming on. Her nipples will be full of milk.She will most likely become restless and may begin digging in the whelping box you have set up for her. If you have not set up a place for her to have puppies you want to do that. A plastic kiddy pool works great is easy to clean and is large enough to contain all puppies as they grow..
Please reply back if you have additional question or concerns.