How's A Dog Pregnancy Time Line?

Average gestation is 59 to 63 days from the first tie (calculator in first link below) though can be a little earlier around 57 or up to 68 (time to be concerned and are more likely to need assistance or c-section at that length and more so on smaller breeds). During the pregnancy some of the standard prenatal care consists of things like ultrasound/x-rays for many reasons having to do with the health of dam and pups, confirmation and knowing whether difficulty is very likely based on the visuals if not a general c-section breed.
During early labor the females temperature will drop to around 98. It is important to know when this occurs since if there are no pups within 24 hours of the temperature drop (active labor) there is a problem and the vet should be called (or if c-section breed that it is time to head in). If the pups are free whelped (non c-section) the dam is examined 24 hours after to be sure there are no complications and retained placenta's or pups (can be sooner if fewer whelped than shown on prenatal visuals) to cause deadly infection. The veterinarian will usually go over the next steps and more common danger signs and problems for the nursing stage at that time.
www.askabreeder.com   
http://drnelsonsveterinaryblog.com/2009/01/01/canine-labor--when-to-call-the-vet.aspx  
www.learntobreed.com  
www.dogbreedinfo.com  
www.dogfoodanalysis.com