First of all, it must be clear that, as a dog’s nature, he is unwilling to relieve himself near his own bed. At the same time, dogs use their sense of smell to find places they frequently relieve themselves and fix those spots. So as they grow older and their activity range expands, they gradually find a relatively fixed place farther from their bed to relieve themselves. There are two methods: one is to fix a spot in the house for the dog to relieve itself, and the other is to not allow the dog to relieve itself inside.
The former allows the dog to relieve itself anytime, but there is always some odor at home; the latter requires taking the dog out for walks more than twice a day regardless of weather, but the house will be cleaner.
Puppies can start training at one month old. Puppies learn to use a fixed spot very quickly, as long as you are patient in the first few days, success is generally achievable.
There are many options for fixed spots. Some designate the toilet floor drain, some use dog toilets bought from pet stores, some use newspapers placed a bit away from the puppy’s bed. I think newspapers are not very absorbent, so I always use diapers, changing them once a day, which is very convenient. At first, you can dab the newspaper or diaper with a little puppy urine or wipe the puppy’s bottom and then place it in the fixed spot. The puppy will find the spot with the smell to relieve itself.
If it does not find the spot, you need to observe carefully. Puppies usually have certain fixed actions before relieving themselves, such as lowering the head and sniffing repeatedly in a small area, walking back and forth, circling, etc. Once you see these actions, pick him up and take him to the designated spot to relieve himself. Praise him after he finishes to let him know he did the right thing. A normal puppy’s life should be relatively regular, wanting to relieve themselves after eating or waking up. Observing this routine also helps you know when the puppy wants to go.

If you want the puppy to get used to going outside to the toilet, it generally should start at 4-5 months old. Before this age, the puppy’s nerves and muscles are not fully developed, making it hard to hold it at home and difficult to educate them to remember. At first, take him out 4-5 times a day, meaning taking him out at the puppy’s usual toilet times so he can relieve himself outside.
If he relieves himself inside, educate him on the spot so he knows you are unhappy. At the same time, clean the spot thoroughly to avoid leaving any odor, using something like 84 disinfectant repeatedly to remove the smell. As the dog gets more used to going outside to the toilet, the number of times you take him out can be gradually reduced but must not be less than twice a day in the end.