The rule is for puppies, however many months old they are is the number of hours they can hold it, give or take. That only applies for the early stages of a dog's life, however. Obviously a 1 year old dog cannot hold it for 12 hours.
Now, I don't think it's possible to train a dog to go outside if you're gone for 9 hours a day. It's just too much to expect out of a little dog. Franklin and Maggie are both potty trained outside and they can only hold it 6-7 hours, max. They are also on the larger side and most likely much older (1 and 4) than your dog is.
If you do decide to try it, I would take him out ever 2 hours and stay outside until he goes. Find a super special treat (ours is cheese) and use it only for pottying. When he's out, keep him confined to one room and watch him like a hawk. If you can't, he needs to be in a crate or a play pen. Until he's potty trained, the key is to prevent accidents before they happen. Any accidents that happen are the owner's fault, not the dog's.
I know it can be frustrating but I'm sure you can figure something out. Good luck! |