My husband I also watch Esme like a hawk. I swear, I don't let her out of my sight! But, it happens so fast and before you can get the word 'no' out of your mouth, there is pee on the floor!
We have had her for about a month and a half. And for the most part, she knows what to do... BUT we still have frequent accidents. Today, we have had two and it's only noon...
It's all about patience and persistence. Good luck on whatever you decide... but from what I have read about yorkies, they can be a bit difficult (but so worth it)!