Just because your new dog is old enough that he should know where to potty doesn’t mean that he actually does. An adult dog has the necessary muscle control to hold it for longer periods of time, but if no one ever taught him the potty training rules then he’s the equivalent of a brand new puppy. Age should not be equated with housetraining prowess, so it’s a good idea to treat any dog new to your home as if he’s still learning the potty training ropes.
If you want to prevent accidents before they happen you’re going to need to watch your pup at all times, including every time they wander off. It only takes one accident to set your training back. Now I know that watching your puppy non-stop isn’t exactly fun & exciting, but being able to catch them before they have an accident is why this method works so well.
Any area that the pup has access to must be kept clear and clean. Put out of puppy's reach anything you don't want him to chew or destroy. Do not allow your puppy to have unsupervised access to 'unchewables.' Do not chase the puppy in an attempt to take something away. Instead provide puppy with her own toys and teach her how to play with them exclusively.
Though it differs by each individual dog this is the time when most will come up with their own little way of letting you know they’ve got to go. It might be crying at your feet, ringing a bell you’ve set up or waiting at the door — just be sure to pay attention to these signals & follow up. Once your dog knows how to get your attention when he’s got to go you can relax a little and congratulate yourself on a job well done.