wait... you need to ask CIC call center about this..
before leaving country, if you go border and got entry to canada as PR, you CANNOT leave the country without PR Card, if you leave you need to get some visa sort of thingy to enter canada from the visa office of the country which you are visiting..
but I m not sure if you leave canada without getting PR from border and enter as new immigrant (definitely before the expiry of your PR visa), what happens then, my understanding is one should be ok.. but do confirm from CIC call center..
Thank you.