Lola was 99% at 6 months, and I would say 100 % now. she only goes outside and since I work from home I took her out a lot and that seemed to make the difference. She is also is the only dog that I have had that does not seem to be a spiteful wetter and belive me they exist. My last male yorkie had full access to two litter boxes which he used all the time, but darn it if I did not take him out with me to get the mail, he would pee the mat in front of the door I went out. Sometimes he would climb the stairs to go up to my bedroom but sometimes he would not, if I went up without him and he started winning for me to come to get him if I took more than 5 min, he would wet at the foot of the steps. It drove me nuts and almost swore me off small dogs for good
Small dogs especially yorkies for the most part are very hard to housebreak, so I wish you luck