=== VERY IMPORTANT===
To crack the interview french is not that much essential, because with basic french knowledge (A1/A2/B1) and good english one can crack that. But the exam which is conducted for regulated profession which comes under professional body will demand at least a level of B2 proficiency.
Check whether your profession is regulated or not here.
http://www.cicic.ca/403/occupational-profiles-for-selected-trades-and-professions.canada
If it is regulated then you have to clear the exam OQLF to get permanent work permit and to obtain a license under your QSW PR.
Read below summary to get better idea:
anyone who didn't complete either a high school or college in a francophone country is eligible for a one year temporary work permit with a possibility of extension. So, it means that even if you qualify according to academic credentials without good french it's impossible to be a chemist, physicist, engineer, doctor whatever in Quebec. To get a permanent permit the candidate has to pass a french exam by Immigration Culturelle upon arrival to Quebec.
candidates must obtain a certificate from the Office québécois de la langue française (OQLF). The certificate is issued to anyone who passes the OQLF examination, which assesses knowledge of French based on the following four criteria: written comprehension, oral comprehension, written expression, and oral expression.
may issue a temporary permit valid for one year to individuals who have obtained their diploma outside Québec and who are declared qualified to practise their profession but who have not been able to demonstrate the required level of French fluency.