A typical gestation for a dog is 58-63 days, so 58 days would be just fine for her to deliver. Right now she is nesting and getting ready to deliver her pups. DO NOT LEAVE HER UNATTENDED!!!! She may be a expert deliverer, but situations can always arise. I am going to post a website for you to look at and refer to throughout the labor process.
Good luck and wishing you a happy healthy litter :)