JT:
This may be slightly different at my kids school because we are in a growing district that hires a lot of new teachers every year but...
My guess is that you will NOT be the only nervous teacher at the school on the first day (or even days). And remember the students will be a bit nervous also. By the time the students calm down and get in tune enough to notice any issues you might be having, you will have gotten your feet grounded your ownself so it will all be fine.
I said this in a MSN session and I meant it: I honestly think you will be a fine teacher. Remember you do have some past experience (working with kids on ballet) and you had the days in the classroom last Spring where you did awesome (once you learned to sit somewhat still -- ha!). You WILL be great PJ. Maybe not the very first day but you will calm down and get settled and then you will do an excellent job.
I'm sure the kids will love you. (Everyone else does -- remember? You tell us that all the time.

)
-- Rob