For somebody who never had a license before, it would be class 7, learner for 9 months, then a probationary class 5 for 6 months and a stage 2 probationary for another 12, see http://www.sgi.sk.ca/sgi_pub/drivers_licences/gdl/gdl.pdf
so somebody who is starting out would not be able to get a commercial license for 2 years and 3 months BUT going by http://www.sgi.sk.ca/sgi_pub/drivers_licences/new_residents.htm
it looks like if he can prove that he already has a license in some country, he can skip over the learners stage and go directly to the probationary class 5 license. Still stands though that he would have a GDL license for 18 months and not be able to get a commercial license until then. That is unless OP has a license from the US, UK, Austria, Switzerland, South-Korea or Germany and can prove that this license is more than 2 years old, he would be able to get a full class 5 license and therefore go on to train for a class 1 license.
I know if he was in AB, if he could prove that he has license from any country for more than 2 years, they will right away let him take the advanced road test and get a full class 5 and after that he can go on to work on his class 1.