I think how fast it will progress will depend on things like the age of the dog and how bad
the hernia is right now, and a vet would be
in the best position to advise you on that. Plus, only a vet can advise you whether he needs surgery and how soon.
Give us a little more information to go on, if you will. People here will help you problem-solve, but you need to get yourself directed down the right path, which in this case is the veterinary path.