Business visa transfer to work visa

Hii Friends, Need urgent advice...
How long will it take to process Business visa to a work visa. as my business visa is expiring during eid holidays and i plan to submit the paperwork to immigration for transfer of visa to work visa on Thursday.
Do i have to leave the country once i submit the papers on visa expiry date?
i think 3 days only.try to renew it b4 eid
Please help!!!!!!!!!!!!!!!!!!!!!!!1