so one's clock/timer is off 
First Stage of Labour
The first stage of labour can last from 4-24 hours. The cervix begins to dilate and uterine contractions commence. Signs include restlessness, pawing, nest building, shivering, turning the head to watch the belly, possibly mild straining and occasionally vomiting. These signs may be quite dramatic in nervous bitches who may seek constant attention from their owners. It is important to realise that all of the changes described above are normal and nothing to be worried about. These signs normally progress steadily until the cervix is fully dilated and the bitch enters second stage labour.

First Stage of Labour
The first stage of labour can last from 4-24 hours. The cervix begins to dilate and uterine contractions commence. Signs include restlessness, pawing, nest building, shivering, turning the head to watch the belly, possibly mild straining and occasionally vomiting. These signs may be quite dramatic in nervous bitches who may seek constant attention from their owners. It is important to realise that all of the changes described above are normal and nothing to be worried about. These signs normally progress steadily until the cervix is fully dilated and the bitch enters second stage labour.