Hi used to raise dogs for many years. And have delivered many puppies it can take 15 min. To normally 2hour many cases much longer you should never see blood or green fluids before the first pup arrives that could be a sign of trouble your dog can be uncomfortable along time in labor by scratching digging ripping her bedding when she begins to push is when she is ready thats what I meant when I said 15min to 2 hours. After she starts pushing when she pushes she will make a little progress each time you might see a water bag come first then puppy will follow only begin to worry if she pushes and never makes progress or if you start seeing blood or green before first puppy hopefully you have had pups before or the mama has had before because its always a little scary hope all goes well and you can write back if you have more questions I don't know if youre in labor yet or just getting ready best wishes and goodluck.
Duration of true labor depends upon litter size. Small litter is delivered earlier in less time than large litter. Labor in dogs can be divided in 3 stages. First stage can be of 6-24 hours during which restlessness and pacing is common. Deliveries of first puppy takes place in second stage. After which she can go for rest for maximum 2 hours followed by delivery of second puppy. This process is repeated until all puppies are born. So, usually It takes 2-6 hours to complete the birth process. After this 3rd stage of labor begins during which placenta is removed.