For dogs that are reactive to people coming to the house, we need to very carefully prepare and advance our training situations.
The home is the “most touchy” place for any dog. It is really important that you do not start your training right at this touchy place, so close to your dog’s threshold.
You want to find the first place that your dog shows reactivity. Nearly never that is when a stranger comes to the door. It usually is when they are in your driveway, or even when you are on a regular walk or in busy places. The dog’s reactivity in those places might be less intense, but still there.
This graphic helps envision your dog’s “circles of reactivity”:
You never want to start training in the red circle. Find the first circle that your dog is struggling with and work inwards from there.
Let’s say your dog is already showing reactivity when someone is at the end of your driveway. Then this is where you need to start your counterconditioning sessions. Only when he has improved significantly, move to right outside your house. And only when he has improved significantly, move inside your house.
Once you are ready to move your training inside your home, pick the most spacious room. Just like during outside counterconditioning sessions, your dog will do much better if he has plenty of space to get away and use his body language to communicate that he wants to be peaceful and non-threatening.
Tight spaces and no options to get away breed escalations.
Some dogs are never able to calmly and successfully navigate greetings right at the door. The space is too small and the emotions (even just happy excitement) too intense. Whether or not your (formerly) reactive dog can navigate door greetings will depend a lot on your home’s layout, too – the more narrow your entry area is, the harder it will be for the dog.
You should consider putting up baby gates that prevent the dog from coming directly to the door, or generally have him in another room when you expect visitors. Then let the greeting happen in your biggest room – usually the living/dining area.