Thanks to those who responded. Actually, just after i posted this, I went in for a second training day at the new job and at the end of the day they decided not to hire me.
The problem is: they didn't train me either!
So my stress derives mostly from these crazy bosses who think I don't need training or don't have time to train me when really I need practice and instructions!!!
I'm starting to think my next best bet will be a family restaurant...or else Applebees? Except I would hate working at such a loud obnoxious establishment...
But it's either that, or give up au pairing, and get an unpaid internship (and resign myself to living at home for the rest of my young life)

If anyone here has waitressed before: please help! Did you just b.s. your way through at the beginning? Or were you naturally amazing at waiting tables? Or did you work some sh***y job until you had some experience bussing?