There are definitely more risks associated with pregnancies in dogs younger than 2 years. However, in the "old" days, it was not uncommon for dogs to breed during their first heat cycle. Quite a few breezed through the whelping process, and delivered healthy litters of pups. But again, it is not advised; and spaying is always the safest and most responsible choice.
With that being said, sometimes things happen. When they do, seeking veterinary care and becoming educated on the whelping process will greatly improve both the mom's and pup's chance for a safe delivery. I think you have every reason to expect a safe delivery if she is healthy...if she receives proper diet, exercise and vet care...and if she bred within her breed size class. If she mated with a large breed dog, a C-section may necessary. C-section are also commonly necessary with certain breeds such as bull dogs. Large head breeds have difficulty passing through the birth canal.
Your vet will be able to do an x-ray to determine the number of puppies, size, etc., and to determine if a C-section will be necessary. If the breeding was recent, and your vet is concerned for the b..ch's safety, he/she may recommend terminating the pregnancy .
If everything looks good, and you and your vet decide that a home delivery is safe, you can expect the pups to be born within 60 to 65 days following mating. I highly recommend that you begin taking the b..ch's temperature about two weeks prior to delivery. If done correctly, you will know exactly when the pups will arrive. Otherwise, the waiting is horrible and you may experience several days of being tied to your house. An inexperienced b..ch should NEVER be left alone if delivery is near. Several situations can arise during labor. Most situations are easy to handle, but can end tragically when not handled.
Normal temp will be between 100 and 102. Within a couple of days before delivery, her temp will drop below 100. Most owners will notice a steady drop of 1 degree every day. When her temp drops to 98 or below (and remains) you can expect the first pup to be born within 12 to 24 hours. There is a wealth of info out there that will help you through each stage of the process. Best of luck!