When you first bring your new puppy home, you might be tempted to delay housetraining (or any training for that matter) until he "settles in." This is a decision you will regret.
The key to housetraining is to start rewarding your dog for pottying in the right place as quickly as possible. The stronger the reward history, the stronger the desire to go in the desired location.
So how to do we build the necessary reward history? It's easier than you might think.
WHERE?
First, we figure out where we would like our puppy to eliminate. You can get really specific here. For example, most people with enclosed backyards prefer that their dog doesn't potty right next to the back door. You can train that! Simply walk your puppy to the desired location on-leash to avoid him wandering into areas that you'd rather him avoid for pottying.
Do this often. Very often - every hour for a young puppy. Another advantage to having your puppy on-leash is that you'll be right there when he does go, so you can begin to throw a potty party immediately. And you really do want it to be a party - cheer, happy talk and dole out lots of yummy snacks (think 10 tiny treats in a row). You can use part of the puppy's daily food ration if you're worried about the extra calories.
If you wait to reward your dog until you get back inside, you're too late. He won't be able to connect the behavior (pottying outside) with the reward (the potty party).
WHAT IF HE DOESN'T GO?
Bring him back inside, confine him to a crate or small room and set a timer for 30 minutes. When the timer goes off, bring him back outside. Give him 5 minutes.
Repeat.
This will take some legwork in the beginning. But remember - the key to housetraining is a strong reward history in the correct location. And since going to the bathroom is, in itself, a rewarding event (i.e. it provides relief), we can't allow the puppies any opportunities to go in the wrong place. This is how housetraining goes south quickly.
MANAGE CAREFULLY.
Supervise him like crazy. Uncrated time in the house is only reserved for puppies who have just pottied (both functions) outside. And even then, it should still be in a kitchen or other small, segmented area of the house and you should still be watching him closely. If something else is demanding your attention, crate him.
CALMLY (BUT QUICKLY) INTERRUPT MISTAKES.
If you do catch your puppy in the act, don't let him finish! Simply say, "Oops!" and usher him outside as quickly as possible. If he finishes outside, it's party time. If he does nothing after 5 minutes, bring him back inside and monitor closely.
BE THE GOOD GUY.
Ever heard the advice to rub your pup’s nose into the mess to teach him that what he did was wrong? This will not work. Period. If you do it immediately after the pup has gone, he will connect the two things (pottying and being punishing) but not in the way you'd hope. Instead, he will learn that pottying in front of you is dangerous. This is how we end up with a pup who simply will not go in your presence, and will hold out until he can sneak off and go in the other room. It's a terrible cycle and definitely not the relationship you want with your best friend.
If you didn't actually see him do it, you're too late. He won't be able to connect the behavior and the consequence at all. All he'll learn is that you are unpredictable and scary. Again, not the relationship we're after.
So to recap, the key to housetraining is a strong reward history in the desired location. We achieve this by 1) deciding where you'd like your pup to go and bringing him there often, 2) crating/confining your puppy unless you can give him your full attention, 3) throwing a party IMMEDIATELY when he goes in the right place and 4) setting yourself up to be the good guy. Follow these rules religiously, and you will have a potty-trained dog very quickly.