So you need to get your work permit first. some open work permits make you eligible for RAMQ coverage without even have a job offer, in other cases that your OWP is not eligible you need a job offer in Quebec. Also as part of the sponsorship program, you need to apply for CSQ. as soon as you get your CSQ, if you hold a valid permit in Canada, it makes you eligible until the validity of your permit.
In either case you might consult with the RAMQ directly at 800 561-9749