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.
Unfortunately, there is no magic length of time or milestone age when a puppy can be considered fully housetrained and there are many factors that go into how quickly a puppy can be potty trained. Your puppy’s age plays a major role during the initial phase of potty training, as a very young puppy won’t have the muscle control necessary to hold it for long periods of time.
One of the biggest mistakes new puppy owners make is expecting their puppy to hold it for longer than he is physically capable. The general guideline for puppy “hold times” is that each month of age equates to an hour of “hold time,” so a two-month-old puppy can hold it for roughly two hours. There are exceptions to the rule; your puppy should be able to hold it for slightly longer period of time at night as he gets older and you pup will need potty breaks more frequently when he’s playing.
You may also notice common behavior problems in your dog such as jumping up, barking, or even aggression. The best way to correct any misbehavior is to interrupt it. Shift your dog's attention to something positive. Try running through cues that your dog has mastered followed by rewards. Keep your demeanor cool and confident, and be clear about what you mean.
The process is the exactly same for older dogs as it is for puppies; prevent accidents from happening by using baby gates and a crate if possible, create a predictable schedule, learn to recognize your dog’s potty signals, accompany your dog outside and immediately reward for all outdoor elimination, properly clean any accidents and supervise your dog until you’re sure that he understands the rules.