[lil fu fu girl]

I am a firm believer in getting your pups to understand commands as early as possible.
Whenever it is time for me to retire, I say "Time for nite-nite".
Both of mine, (7yrs, and 7months) know exactly what that means now. They go up and climb in my bed and get settled.
Using consistent commands for as many normal activities as possible will get them trained in no time. Yorkies are very smart and key in on intonational sounds. So essentially the more you use the same vocabulary for commands, the more they will learn.
For now, I would not only use the mister(Patti's suggestion), but also use a command with it, that way she will connect the two, and be able to identify the command so that the mister is no longer needed.

Best of luck and hope this helps some...