Unfortunately the official answer is that with CSQ you cannot get an open work permit. You are LMIA -exempt so it makes it easier for your prospective employer to help you obtain a work permit, but it will be a closed one. Or employer specific. That's the deal. In other provinces PR applicants are eligible for something called bridging open work permit, but as usual, this does not apply to Quebec. You can always try to apply for it, a few have succeeded but others got rejected because as I said, Quebec PR applicants with CSQ are not eligible for open work permits.