I just wrote a PM to someone else here on litterbox training yesterday. I know everyone do it differently and this I am just speaking out of my experence. I hope this would help you with your puppy.
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1. No dog litter just the box (line with newspaper)
The litter piece is too big for our puppy to stand on and she likes to chew on it too much. So we put newspaper in the litter box and it works very well.
2. Let puppy pick the spot
It's not easy for puppy to get the idea of where you want them to go at first. So I found it much earlier just let them pick a spot anywhere in their area. I fence off a small area in our bathroom (it's a good size bath - way too big for a puppy). Put her hard carrier, a few toys and water in there and then lined the rest of the area with newspaper. Ours used to sleep in her carrier when she was little and we put blanket in it to make it more comfortable. When she needs to go, she would pick a spot in the fenced off area. Pretty soon you would see a pattern as where she prefers to go.
3. Go slow
Slowly reduce the area that's covered by newspaper from where she has never "went" on. Take your time!! If you move too fast, she would go on the naked floor. Once the paper has been reduced to about the size of the litter box, it's time for litter box training.
4. Sizing the litter box
I have heard of some puppy went outside the litter box before. If that should happen, it probably means the box is a bit too small for him/her. My baby was a little over 2 lbs when we start little box training and we use a toy size (15"x20"x5") Purina Secondnature dog litter pan which we got at Petsmart. She is almost 7 months now at 4 lbs and the size of the litter box still works for her. I don't know how big your puppy is now so I can't tell you what size you need. However, the toy size was meant for dogs up to 6 lbs. There are also miniature size (20"x24"x5" for dogs form 6 to 15 lbs) and standard size (24"x28"x9" for dogs up to 35 lbs) available. I don't really think Yorkies needs the standard size but some of them like to have a larger area to do their potty dance.
5. Introduce litter box
Paper in the box would be a new idea to your puppy so you will have to keep an eye on it at first. I found it helpful if you put the newspaper on top of one that has been soiled - in the box of course. When the puppy needs to go (they usually circle around a bit), put her (or him) in the litter box so they would know where to go. Mine actually would jump in and out of the box for a while before she would take her position in the box. I called it the potty dance. Don't be too concern about the jumping part. You can actually help by putting the puppy back in the box if he/she shall take "position" outside of the box. My got the idea pretty quickly since she was paper trained first and the box is where she would find her paper now.
6. No full run of the house – not yet
I think the key to house training is not to let your puppy have full run of the house until she/he is pretty reliable. If you can't watch the puppy, she/he would stay in the fenced area. That way not only they won't have accidents, they won’t get into trouble either.
I am not going to say it's easy to potty train a Yorkie. It really takes time especially when they are young they just can't hold it for very long. My puppy was peeping in her carrier in the middle of the night where she sleeps at first. Although she would cry to let me know that she's gotta go, I never could get there in time (and she was in our master bath

). That's why I fenced off an area for her to begin with. It turn out to be a great idea and she never peep in her carrier again.
We actually have two litter-box. At the beginning, I put them side by side for her. When I am unable to clean it up for her right away, she would use the other one - instead of go on the floor. She doesn't like to use a soiled paper unless it's dry up already.
Now as she is older and doesn't have to go so often, we have one box upstairs and the other downstairs just to make her life easier. I am happy to say she is house trained now.
Another good thing about using paper instead of dog litter is you can get newspaper almost anywhere. We would put down newspaper for her whenever we are visiting friends or even in my office and she would go on the paper. You got to show her where the paper is and how to get there though. I would definitely use the litter box + paper combination at home and NOT just the paper. That way, you wouldn't have to worry about messy floor if she missed (sometimes, they have their paws on the paper or pee wee pad for that matter but their bottom is off).
Anyway, that's my experience and I hope it helps. Let me know if you have any questions or if you need more information.
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Congret on your new baby and have fun with him.