Growth plates will close regardless of whether they are spayed or neutered. The timing of spaying is a consideration, however.
All of my dogs over the years have been spayed or neutered. I also thought spaying before the first heat was better. However I now would wait until the growth plates closed. In a small dog like a Yorkie that might very well happen by eight months, and you can do a simple X-ray of the tibia to be sure.
The link I have attached is very interesting, and I like the author. Spaying and neutering studies are mostly done on large breeds, but I still find the information worthwhile.
Congratulations on your new puppy, Taylor.
http://www.caninesports.com/uploads/...tions_2013.pdf