I taught elementary school for 10 years and that was after 1 1/2 years of substituting first.....and for me, there is no way that I could have had anytime for a puppy. I was in my classroom non-stop. I would stay late and be there on the weekends. You could take your pup with you on the weekends.
I don't know what you are teaching or how demanding your schedule will be but it may not be the right time to take on a puppy. You may want to get used to your new schedule and then decide if you have enough time to allow for a new puppy. Believe me, I would love to encourage you to get a yorkie but if your teaching demands are anything like mine were, it may not be the right time. Just something to think about.