My Mason's ears finally went up when he was about 6 months. I had to make sure all the hair around his ears were clipped SHORT so that hair did not weigh down the ears. For about a month, one ear was up and the other was down (this was quite a funny sight
) so I kept massaging one ear.
I have seen some yorkies with their ears flopped down and I think it's cute...but I read somewhere that dogs with ears flopped down are more prone to infections and ear mites. I also remember reading that when the dog is teething, the ears go up and down.
On her website, Terry gives a great explanation on how to tape your baby's ears, if you want to.
http://www.shooterdog.com/alexfaq2.htm
Hope this helps!