We will be adopting a 2 1/2 year old Chihuahua. The only concern I have is that her previous mom taught her to go potty ON A PIECE OF CARPET! I don't see how she will be able to tell the difference between a "piece" of carpet and the whole carpeted townhouse. Will I be able to break her from this? I know it will take a lot of consistency and I will be using crate training and taking her out every 2 hours and 15 minutes to 1/2 hour after her meals for the first weekend. But because she was initially trained to use a carpet, will I have any hope?
I personally would completely retrain her, but you might see if you can get the piece of carpet that was used from the previous owner. She will know the difference from your carpet by the smell. Then use it like a puppy pad and begin training her to go outside on the piece of carpet and slowly get her used to using the grass. I'm not certain if this will help or not, but it might be worth a try.
It sounds like you will be starting all over, IMO crate training makes life much easier. Maybe you could get some baby gates and keep her in an area of the house that doesn't have carpet for awhile. When my dog was younger, we used gates to keep him in the kitchen until he was housebroken. Congratulations on your new dog!