Ideally, the time to start training is while they're with their dog mothers. If memory serves, the mother dog stops taking care of that herself around the same time solid food is slowly introduced (4-5 weeks or so). If puppies come from a family home, they're usually well on their way before they go to their new home around 8-12 weeks.
If a puppy hasn't had that early training, maybe has been living in a cage at a pet store or breeder or shelter, it's usually a bit more difficult. They've been forced to eliminate right where they live, so they kind of forget that's not what they want to do. It's instinct for dogs NOT to 'go' where they live, to avoid leaving their scent (think predators). The longer a puppy or dog lives in a cage all the time, the harder it is to housetrain them.
The big key is taking them outdoors frequently. Depending on the age, about every hour or two. Praise them and give them a treat when they eliminate outdoors (or on the pee pad or indoor grass mat, if that's the plan). Puppies need supervision pretty much constantly, either by you or by their crate/cage. You'd be surprised what sort of trouble a young puppy can get into while your back is turned for just a minute. If your puppy starts to walk around in circles or heads for a corner or under a table, say "outside" in a loud but friendly voice and get puppy outside quickly. If you're pee pad training, direct puppy to the pee pad or wherever you're wanting them to go. Praise puppy for doing the right thing when they do... make a big deal of it, ("good puppy, good boy, Rover" , etc. Give a small treat and affection). Positive reinforcement.
When you catch puppy in the act, use whatever word you're using in a stern but not scary voice ("outside" or "wee wee pad", etc.) and get them to where they're supposed to be. I've always used the same sound to get my dogs' attention, sort of a 'eh-eh'. They learn quickly that means stop what you're doing. Even if the deed is done, get them outside. Since you're watching puppy at all times that they're not in their crate, you should be able to avoid too many accidents. When you do discover an accident after the fact, ignore the puppy and clean up immediately. Use a good odor-removing product (I like Nature's Miracle)that includes ingredients that help deter reoffending with pheromones or something. You don't want puppy deciding that a certain corner in the bedroom is their toilet. Then take puppy outside.
Puppies are like young children. The only time you should raise your voice to them is when you're trying to prevent something dangerous or very serious. You want them to recognize that when they hear THAT voice, they need to stop and pay attention. Don't put your dog's nose or face in or near their excrement and scold them. And, of course, you never hit or otherwise cause physical pain to a dog unless you're being attacked by one.
Always take your puppy out the same door, so they learn that's where they go when they need to go. Some people find hanging a small bell on the doorknob and ringing it when they take puppy outside and teaching puppy to do the same helpful. Dogs learn to associate many things with certain sounds, so it makes good sense that it helps reinforce and builds memory.
Good luck! Toy breeds are known to be more difficult to train, but Pomeranians are usually pretty bright and very eager to please their owners.
The tether method works best. This is where puppy is constantly on the leach and the leach is in your hand. This keeps you focused on the dog. So you will know when the dog needs to go outside. Should take it outside every 2-3 hrs and directly after eating/drinking. It should never be free to roam the house until fully trained. If not on the tether they should be in bed. (One they cannot get out of by themselves)
