Are you in Canada? If not, is your employer willing to support your application for SINP from abroad? Or you plan to land in Canada first then get the minimum required of 6 months exp under the Existing Work Permit Sub-Category of the SINP? Well, if this is the case, I suggest that for your first few months of work, and you have been doing good, try to ask your employer to start the SINP process which has become complicated since 2012. Mind that it's LIKE a LMO/Work Permit process wherein the Saskatchewan employer should register first with the SINP employer site and apply for a "Confirmation of Job Approval" from the Sask government (approval for the position only), which takes 2-6 months already, then once receiving this, the employer should submit your name to Sask govt. for another process (2 wks - 2 months). Once you have that Confirmation of Job Approval with your name on it and you have worked for a min of 6 months as skilled worker, then that's the only time you can submit your application for SINP which takes 1 - 12 months depending on employee's circumstances (those work permits expiring soon get processed faster even as little as 20 days, but mostly after the 3 months mark). Also, the SK govt has established quota for number of applications to be processed each year. So, it entirely depends on your situation and luck, maybe.
SINP or CEC? It depends on how sooner you qualify and gathered required documents. In our case, my spouse worked in SK in April 2012, 6 months work exp in October 2012 but weren't able to apply for SINP yet as we were waiting for the confirmation of job approval. Our employer applied for it in September 2012, followed up from SK govt. in February 2013, and got it only in May 7, 2013. Because of this tedious process, my spouse opted to take the English test in April 2013 and apply for CEC as that time, my spouse had worked for more than one year already. When we got the SINP confirmation of job approval, our CEC application is already complete, and ready for submission on May 15. Had we waited for SINP, we might still be waiting for the nomination certificate 'til now. Just try to research the whole process and determine what's best for your situation. For as long as you qualify, you can take either route, even both. Good luck.