No, its not too late. Are you home during the day to commit to full time training? If so, then it should happen even faster. Yorkies are VERY smart
I suggest going to the petstore and buy a really yummy treat - I prefer Wellness Pure Rewards, they are soft and jerky like with a strong smell (I cut them in half to get more from the deal). Anyway, use these treat as GOOD POTTY BEHAVIOR and ONLY for that
If you want to train her outside, take her out every 1/2 hr to start, bring the treats and when she goes, tell her "go potty" and when she is done, praise her and give her a yummy treat. Trust me, this works