They are capable as soon as they go into season but it would not be a good thing at all and considered very bad breeding. The earliest time it would be acceptable for her to have a litter would be her third season to 2 years of age.
You would use the time to learn about being a good breeder, make sure she is even a good candidate for breeding once she's more mature and it's a good idea to have a pretty substantial savings to cover all the expenses when you intend to have a litter. Based on your question you would have a lot to learn in what won't end up seeming to be that long but it's a good sign that you did ask. You don't have to have a litter as soon as she is able though. If you need to skip another season that is best and just what you would need to do.
Your breed parent club is a good place to start and it would be a good idea to find a mentor or two to help you out along the way and to learn the things you would need to so you can be sure it's something you want to do and know enough to have good pups and to have a lot less risk to your girl. Breeding responsibly is a lot more complicated than it first seems it would be and there is a lot to know.
Breeding is always a risk of their life but the less you know about what you are doing the more likely that is, for the pups as well as her. Yorkie's also need c-sections pretty often due to their small size even when breeding within the standard guidelines of a female of at least 5 pounds with a smaller male. It is considered to high risk to breed a smaller female and not in their best interest.
You will be creating lives that you have a lot of responsibility for how their futures turn out. You need to know enough to give them the right start, the best future and to be able to provide support to the new families throughout those pups lifetimes. That is a huge part of keeping them out of shelter and rescue.
The majority of the responsibility, their health, their homes, their behavior, whether they end up in the shelter 8 or 9 times out of ten (with millions and millions in shelters) even though they are no longer in your home (and you probably have no idea) it can almost all be traced back to something you as their breeder may or may not have done or known most of the time.
It is important and worth it to make sure you are doing things the right way to try and minimise all of that. Here are some links and more links within the links to get you started on some of the basics and considerations. Good Luck whatever you decide to do when the time comes.
http://www.ytca.org/faq.html http://www.ytca.org/mainview.htm q9457747.html#a3232514
http://www.caninehealthinfo.org/brdreqs.html?breed=YT
http://www.barkrescue.net/teacup.htm
http://www.lowchensaustralia.com/
http://www.terrificpets.com/forum/36630.asp
http://www.terrificpets.com/forum/16184.asp
q1475322.html
http://www.terrificpets.com/forum/45586.asp http://www.learntobreed.com/ http://www.woodhavenlabs.com/breeding.html http://www.dogplay.com/Breeding/ http://www.wonderpuppy.net/1breeding.php q3388198.html
q3525724.html#a2810229 q1679449.html#a2947871 q5851064.html#a3054016
q2722771.html#a3046267
q5762034.html#a2906893
q5956275.html
q4267050.html#a3103682
http://www.wildheirlabradorrescue.org/readingroom/what-is-a-back-yard-breeder.php
http://members.tripod.com/antique_fcr/goodbreeder.html
http://www.boxerworld.com/rescue/excuses/
http://www.gsdca.org/german-shepherd-dogs/choosing-a-puppy/types-of-breeders http://www.21stcenturycares.org/backyardbreeders.htm
http://www.petfinder.com/index.html
You would use the time to learn about being a good breeder, make sure she is even a good candidate for breeding once she's more mature and it's a good idea to have a pretty substantial savings to cover all the expenses when you intend to have a litter. Based on your question you would have a lot to learn in what won't end up seeming to be that long but it's a good sign that you did ask. You don't have to have a litter as soon as she is able though. If you need to skip another season that is best and just what you would need to do.
Your breed parent club is a good place to start and it would be a good idea to find a mentor or two to help you out along the way and to learn the things you would need to so you can be sure it's something you want to do and know enough to have good pups and to have a lot less risk to your girl. Breeding responsibly is a lot more complicated than it first seems it would be and there is a lot to know.
Breeding is always a risk of their life but the less you know about what you are doing the more likely that is, for the pups as well as her. Yorkie's also need c-sections pretty often due to their small size even when breeding within the standard guidelines of a female of at least 5 pounds with a smaller male. It is considered to high risk to breed a smaller female and not in their best interest.
You will be creating lives that you have a lot of responsibility for how their futures turn out. You need to know enough to give them the right start, the best future and to be able to provide support to the new families throughout those pups lifetimes. That is a huge part of keeping them out of shelter and rescue.
The majority of the responsibility, their health, their homes, their behavior, whether they end up in the shelter 8 or 9 times out of ten (with millions and millions in shelters) even though they are no longer in your home (and you probably have no idea) it can almost all be traced back to something you as their breeder may or may not have done or known most of the time.
It is important and worth it to make sure you are doing things the right way to try and minimise all of that. Here are some links and more links within the links to get you started on some of the basics and considerations. Good Luck whatever you decide to do when the time comes.
http://www.ytca.org/faq.html http://www.ytca.org/mainview.htm q9457747.html#a3232514
http://www.caninehealthinfo.org/brdreqs.html?breed=YT
http://www.barkrescue.net/teacup.htm
http://www.lowchensaustralia.com/
http://www.terrificpets.com/forum/36630.asp
http://www.terrificpets.com/forum/16184.asp
q1475322.html
http://www.terrificpets.com/forum/45586.asp http://www.learntobreed.com/ http://www.woodhavenlabs.com/breeding.html http://www.dogplay.com/Breeding/ http://www.wonderpuppy.net/1breeding.php q3388198.html
q3525724.html#a2810229 q1679449.html#a2947871 q5851064.html#a3054016
q2722771.html#a3046267
q5762034.html#a2906893
q5956275.html
q4267050.html#a3103682
http://www.wildheirlabradorrescue.org/readingroom/what-is-a-back-yard-breeder.php
http://members.tripod.com/antique_fcr/goodbreeder.html
http://www.boxerworld.com/rescue/excuses/
http://www.gsdca.org/german-shepherd-dogs/choosing-a-puppy/types-of-breeders http://www.21stcenturycares.org/backyardbreeders.htm
http://www.petfinder.com/index.html