If you get the Scottie, would you still get the yorkie in the next few months are would you not get a yorkie(or any other dog for that matter)?
If the yorkie breed is really where your heart is, and you all can only get one, I would wait until you are ready for the yorkie...you don't want to be in a position where you've gotten the scottie then later regret(for lack of a better word) it because that yorkie urge is hard to lose.....I don't doubt you wouldn't love the scottie no matter what but if you have to get 1, I'd wait..
Good Luck in whatever you decide!