There are two forms of sponsorship: inland and outland.
At the present time, inland sponsorship requires 9 months to complete the first stage (AIP) at which point you would be eligible for an open work permit. Second stage requires 8 months to complete. I will note that the inland times are decreasing and I saw someone yesterday report they received AIP in just 7.5 months.
At the present time outland sponsorship requires 2.5 months to complete the first stage but you are NOT eligible for an open work permit. Second stage takes about 12 months to complete (for 80% of cases, although some cases are completed more quickly.) You can work once you receive permanent residency via this path. You can remain in Canada on visitor status generally and many partners from the US do so quite successfully.
If you wish to work before you have an open work permit you would need a closed work permit. This could either be a NAFTA-qualifying work permit (assuming you have the professional skills to qualify for a job that meets NAFTA work permit requirements, see FW 1 "Temporary Foreign Workers" on the CIC website for details) or if you can find an employer willing to obtain a positive Labour Market Opinion letter (LMO) then you could obtain a work permit in the interim.
I hope this helps.
Good luck!