Day 9, for the majority of Yorkies - is too early to breed. Also with a small stud it is unadvisable to let him do this all by himself as he can be injuries. The girl should be held, with the index and middle finger of one hand on each side of her vulva and the other hand holding her front leg. This way you can tell exactly where the stud is "hitting" and how firmly and make adjustments as needed. With a maiden girl - the male must "hit" her firmly in order to both enter the vulva and to break the hymen. When entrance has been made, I grab the male under the base of his tail and pull toward me in order to push him in farther and hold him there for a moment or so until the tie is accomplished. After that I just hold the girl and talk to both of them until it is over. (Sometimes up to an hour)
It is a good idea to use a very experienced stubd with a maiden as an inexperienced one often doesn't have the aim and patience down yet.
FYI - The girl isn't ready to be bred until her discharge has turned to straw color (or in some cases has stopped) and the vulva has begun to soften. The average day for my girls is from 12 to 14 days from start of color. If you do saliva slides - the ferning should be well on its way when the time to breed is right.
Best of luck!
Charlie