How bad is it to switch a first year math teacher to "floater" 2 days before school starts?

Question

What should I do?

Answer 1

Last minute staff changes are common as last minute enrollment numbers come in - and the newbie always gets shafted.  Just the way it is.

Look at it as a chance to be the "hero" to your principal, suck it up, and do the best job you can, and you won't be the newbie next year.