two feeding questions

[Them and Us]

i have two questions today. i ask so many questions here all the time. one is will a snake refuse to eat at first when moved to a new enclosure. i moved my BCI to a new igger enclosure and i went to feed him today. i haven't been keeping to a perfect schedule of feeding but he/she always takes it anyways. I'm going to try to get my snakes on a every thursday rotation. but anyway i put him in his box with his food left him for a good hour and still no go. any ideas? i also thought well maybe he just isn't hungry. my other question is how do you determine the size of the mouse/rat. I can feed the boa two large fuzzies but can he take a full grwn mouse. i don't know. any wya to determine? i heard something about the fattest part of the body or something or other. thanks. Todd.