I agree with Dee Dee. Havanese are not particularly troublesome to potty train IF you don't let them have accidents to start with, and IF the breeder has done a good job starting their potty training.
Supervising the puppy "almost all the time" is not enough. The puppy MUST either have EYES ON supervision or be confined. No exceptions. People who do this find that they train pretty fast. People who let them "sneak away" and potty somewhere in the house can find that they are very, very difficult to train. Some people let it go for so long that it is almost impossible to train them not to.
And you are right, it's much easier to teach puppy where it SI Ok to go than to teach him where NOT to go. That's why it takes total supervision and/or confinement.
My older boy was fully reliable by about 6 months... it probably took us longer because he was our first dog. Our second girl trained so fast that I hardly know when it happened.
Our puppy was doing really well, then had two UTI's, which resulted in a LOT of accidents that she just couldn't help. (she was peeing every couple of minutes, poor thing!) That did set her back, and we had to go back to very close supervision and confinement again. She is now 9 months old, I can't remember when she last had an accident, but she is still always closely supervised except in the rooms where she has proven herself reliable. (kitchen, my office, her ex-pen or our bedroom) We are JUST starting to allow her supervised freedom in other parts of the house, right after we know she has potted, and still supervised. As she continues to show her ability to use these spaces appropriately (and that doesn't just mean not peeing... it means not chewing on oriental rug fringe, furniture, etc.
) she'll be allowed more freedom.
I think she's REALLY close. By mistake, the other day, someone put her in her ex-pen when we went out, and we came back to find that the ex-pen gate had not been latched, and she had been loose for 4 hours! She had been a very good girl, and had not gotten into any trouble. She asked to go out immediately, so I know she didn't potty anywhere while we were gone either! I still wouldn't purposely leave her loose at this age, though. (I don't even leave the adult dogs loose when we're not home... they get gated in my office)