do you have anyone riding hardboot setup near you to help you on first day?
it is ok to use bunny hill first day
set forward lean on front boot the least possible (almost straight) - rear boot 2 clicks more aggressive
your hardboot stance will be narrower than your softboot one
you can think about transition soft->hard e.g. get your stiffest board, ride it with alpine bindings and boots ... stance angles something like 45/37 ... in this case you will have only half of setup you unfamiliar with