First of all, WELCOME TO YT!!!!!
Now, with a couple of issues, we free feed in our house...let them eat when they want. Especially with a pup this young, you want them to get all the nutrients they can and also going that long without eating could trigger a hypoglycemia attack. Do you have nutrical on hand? If not, you can get it from your vet.
Secondly, it's impossible for a 12 week old pup to know what it's suppose to do and where it's suppose to potty. That's like expecting a 3-6 month old human to be potty trained. It just isn't possible. It's great that you're starting the training so early and you must be consistent. It can take up to a year to fully train a yorkie. In fact, my Gracie who will be 2 in March went on my bedroom carpet yesterday becaue it was raining outside and she didn't want to get wet.
